Sarcopenic obesity (SO) is defined as a combination of low strength and muscle mass along with excess adiposity. Our study aimed to determine the prevalence of sarcopenic obesity in candidates for bariatric surgery, according to ESPEN/EASO criteria using bioimpedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA). Retrospective study of adult patients (18–60 years) candidates for bariatric surgery (BMI ≥40 kg/m2 or ≥35 kg/m2 with associated complications). Adiposity was assessed by the percentage of fat mass by DXA, according to Gallagher's cut-off points. Muscle strength was measured by hand grip according to Sánchez-Torralvo, Dodds, and <-2SD cut-off points of healthy reference population. Muscle mass was determined by DXA (ALM/weight according to Batsis) and by BIA (SMM/weight according to Janssen and according to reference population). In addition, the agreement of the different diagnostic methods of sarcopenic obesity was analyzed. A total of 124 subjects were included in the study, with 71.8 % being women. The overall mean age was 42.6 (SD 8.9) years. SO prevalence was found to be 13 %–22 % applying BIA with the SMM/weight equation according to Janssen, 14 %–23 % utilizing BIA with the SMM/weight equation according to the reference population, and 13 %–23 % employing DXA with the ALM/weight equation following Batsis criteria, depending on the specific hand grip strength cut-off points used. In general, we found good or very good concordances with the different diagnostic methods (with kappa values between 0.6 and 0.97). The prevalence of SO according to ESPEN/EASO criteria in candidates for bariatric surgery was 13 %–23 % based on the diagnostic method and cut-off points used. Display omitted