AbstractThis work highlights using a domestic microwave oven to determine moisture in fish tissues. Also, it compares it with other gravimetric methods established employing a conventional oven (AOAC) and infrared radiation. The optimization of the microwave method was performed utilizing a two-level full factorial design. The AOAC method, which uses a temperature of 105 °C, requires 130 min for the analysis, while the microwave method can be done in 2 min. Intraday and interday tests evaluated the precision of both methods. The determination of the moisture of the fishes Cynoscion acoupa, Argyrosomus regius, Carassius auratus, Sardinella longiceps, Thunnus, Merluccius, Caranx latus, and Brachyplatystoma vaillantii was performed using the microwave and AOAC methods. The analysis of variance and the paired t-test showed no significant differences in the results obtained using these two methods. Also, moisture in other fish tissues was quantified using microwave radiation.Keywords: Conventional ovenfishinfrared radiationmicrowave radiationmoisture AcknowledgmentsThe authors thank the fellowships and financial support from the Brazilian agencies Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) (Finance Code 001), and Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB).Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis study was supported by the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico; Fundacao de Amparo a Pesquisa do Estado da Bahia.