Infrared spectrometry (IR) became a workhorse to characterize microplastics (MPs) worldwide. However, reports on the experimental conditions to measure them decreased alarmingly. As complete, relevant information on the instrumental setup determining IR spectra is crucial for scientific reproducibility, ca. 50% of the papers that reported FTIR to measure MPs were evaluated and it was found that most studies cannot be replicated due to missing experimental details. To ameliorate this, the most critical parameters influencing IR spectra are depicted, their impact when matching a spectrum against databases exemplified, and, following efforts from other scientific fields, a minimum information for publication of IR-related data on MPs characterization (MIPIR-MP) is proposed, along with a brief, simple paragraph to resume the most critical information to be reported. This can be used to improve the worrying figures that point out to a reproducibility crisis in the field, as disclosed by the survey. •Studies on microplastics lack information on IR measurement setup parameters•Around 25% of published papers do not offer useful instrumental information•A lack of understanding of basic IR parameters might affect polymer identifications•The quality of reported data on microplastics is compromised•A paragraph is proposed to minimize the lack of IR instrumental information