Active or Passive Voice in science papers

As a STEM academic, you may not be familiar with the differences in passive and active voice writing styles. Here I describe their differences and when and where to use them to enhance your scientific paper.

The boy is being held aloft by his dad. He feels like superman.

What are the active and passive voices?

According to CMOS, “Voice shows whether the subject acts (active voice) or is acted on (passive voice)—that is, whether the subject performs or receives the action of the verb.”

For example,
“She (subject) studied (verb) nitrogen-containing heterocycles for her dissertation research.” —Active
“Nitrogen-containing heterocycles (subject) were studied (verb) for her dissertation research.”—Passive

In the first example, the subject “her” is emphasized. The subject has acted (studied) on the direct object “nitrogen-containing heterocycles.” In the first example, I am telling a story about her (maybe this is for an author biosketch?). But in the second example, the subject is now “nitrogen-containing heterocycles,” and it is being acted on by “her.” This is the passive voice. The passive sentence is about the “nitrogen-containing heterocycles” not about the researcher.

Now that you know what the difference is between the two voices, you may be asking, “why you should I care?” Because you must advocate for your science, and you must tell the most impactful, clearest story you can in order to reach your target audience! Below, find out how the active and passive voices are used for clarity and impact.

Active or Passive voice in science papers?

Historically, science papers were written in the passive voice. This may seem odd because the passive voice is often considered inferior (CMOS) or weaker and more convoluted. According to “Writing Science” by Joshua Schimel and “The Craft of Research” by Booth, Colomb and Williams, the push to use passive voice stems from the belief that passive voice is less biased and more objective—both necessary in the sciences. But as Schimel states, how you analyze the data needs to be unbiased and objective, not how you write about it.

Incredibly, the argument of whether active voice is appropriate in science papers has been continuing for decades.[1,2,3] The current consensus from journal editors is that scientific articles should be written in the active voice, but the passive voice still has a place in scientific writing.[4]

Keep reading to find out how to use the active and passive voices in your science papers.

When to use the active voice

He windsurfs as much as be can.

The active voice should be reserved for the Introduction, Results/Discussion, and Conclusion sections of a paper. Due to the inherent complexity of science, these sections should be direct and clear for the most impact: active voice is usually more direct than passive voice.

In the introduction and conclusions section, you can give an appropriate background and summary of your research using active voice constructions such as
“Here, we describe…”
“We investigated…”
“In 2025, Smith et al. reported…”

As stated in “The Craft of Research”, in the Introduction, Results/Discussion and Conclusion sections, the authors are “entitled to suggest, prove, claim, argue, show, and so on.”

Here’s an example of a sentence you might find in the Conclusions section. “We optimized the reaction temperature, solvent, and additives to obtain the best yield of product.” The passive construction isn’t as impactful: “The reaction temperature, solvent, and additives were optimized to obtain the best yield of product.”

It’s important to note that repetitions of first-, second-, or third-person pronouns or names as the subject in every sentence become fatiguing. To retain your readers’ interest, vary the subject. Science writing doesn’t require that a “person” always be the subject that is performing an action. Other possible subjects can be tables, figures, reactions, experiments, and so on.

“Table 1 contains the reaction rate at multiple temperatures.”
“NMR spectroscopy helped elucidate the compound structure.”
“The material is unstable and it decomposes over time.”

When to use the passive voice

When there is no wind, he is pulled by a boat.

It is generally agreed that the Methods section can be written in the passive voice because the passive voice shifts the emphasis from the “doer” to the object. The object (material, experiment, analysis of results) is now the “main character” of the section.

Why is the object the main character? Because the purpose of the Methods section is to 1) relate what was done and 2) provide repeatable steps so that others may replicate the study. Hence, the experiment, analysis, product, crystal, spectrum, and so on is more important than the “doer”. The authors are simply giving a neutral, necessary account of the events and outcomes of experiments that can and should be repeated. Thus, in this context, it is unnecessary to specify who did the experiments.

For example, “We heated the solution to 300 °C,” may be appropriate in the results section, where the authors are comparing their research to the literature or presenting it for the first time (i.e., “We did this and found this.”). Notice that the subject is the first word of the sentence. Usually the beginning of the sentence contains the most important information—when the reader is paying the most attention.

If we start the sentence with the object, it becomes passive: “The solution was heated to 300 °C”. This simple statement emphasizes the “solution” over the doer by placing the object first and using the passive voice.

Here’s another example, “The residue was vacuumed dried overnight in an oven, and the product was obtained in 85% yield.” In the Methods section, the science is more important than the researcher!

Use active and passive voice to be most effective

The active and passive voice should be used throughout your paper with most of the passive voice being in the Methods and most of the active voice being in the Introduction, Results/Discussion, and Conclusion sections. However, to retain your readers’ interest, you may need to occasionally mix the style. Varying sentence structure makes text more interesting. Interspersing the passive voice with the active voice, shifts perspective, manages the flow, and ultimately piques interest.

Here's a simple example.
“After determining that XX is the best catalyst for this transformation, we investigated the substrate scope. The substrates tested and respective yields of product are shown in Table X.”

I chose to write the second sentence in the passive voice because the “substrates” and “products” are the main character NOT the Table.

Where do you stand on this issue? Share your opinion by commenting.

1. Hudson, R. The struggle with voice in scientific writing. J. Chem. Edu. https://doi.org/10.1021/ed400243b (2013)
2. Leather, S. R. The case for the passive voice. Nature 381, 467 (1996).
3. Pearlman, A. M. Passive voice. Nature 382, 108 (1996)
4. Sainani, K., Elliott, C. Active versus passive voice in scientific writing. ACS Webinars. ACS. 2015 April 8. [2025 Feb. 15]. https://www.acs.org/acs-webinars/library/active-passive.html