Introduction and objective: The cold chain of immunobiological agent conservation occupies a strategic position in the immunization system and, therefore, needs to be evaluated. This study psychometrically evaluated the Immunobiological Agent Conservation Assessment Scale (Escala de Avaliação da Conservação de Imunobiológicos-EACI).

Methods: Methodological study carried out in Minas Gerais, Brazil, including 275 immunization rooms, divided into three stages: (a) pilot study; (b) internal consistency and temporal reproducibility; (c) criterion validity and structural validity.

Results: The EACI items were analyzed for comprehension and clarity; presenting internally consistency (Cronbach's alpha: 0.72 [95% CI: 0.666-0.763]) and temporal reproducibility (ICC: 0.948 [95% CI: 0.911-0.981]), in addition to explaining 72% of the variance and discriminating the groups criteria (p = .0025).

Conclusion: The EACI is psychometrically reliable and valid and is the first assessment instrument available for this construct.

Keywords: immunization; nursing; psychometrics; refrigeration; vaccines; validation studies.