Objectives This study psychometrically evaluated GeneralSelf-Efficacy (GSE) Scale in patients planned for bariatricsurgery in Sweden.Design A cross-sectional psychometric study. Thepsychometric evaluation was guided by the COnsensus-based Standards for the selection of health statusMeasurement Instruments checklist for health-relatedreported-patient outcomes.Setting Three bariatric centres in Sweden.Participants Adult patients≥18 years old scheduled forprimary bariatric surgery (with sleeve gastrectomy orRoux-en-Y gastric bypass).Primary and secondary measures Psychometricproperties of the GSE.Results In total, 704 patients were included in theanalysis. Mean values for GSE items were 2.9–3.4 and themean GSE sum score was 31.4 (SD 4.7). There were nofloor or ceiling effects. Cronbach’s alpha was 0.89. Menreported a higher mean GSE than did women, that is, 31.2(SD 4.8) for women versus 32.1 (SD 4.3) for men, p=0.03.Correlation coefficients were weak or negligible: GSE andmental component summary score of 36-Item Short FormHealth Survey (SF-36)/RAND 36, r=0.18 (p<0.00); GSEand physical component summary score of SF-36/RAND36, r=0.07 (p=0.138); GSE and obesity- related problemscale r=−0.15 (p=0.001) and GSE and level of education,r=0.04 (p=0.35). Confirmatory factor analysis indicateda one-factor construct with a satisfactory goodness of fit,that is, Comparative Fit Index=0.927, root mean squareerror of approximation=0.092 and standardised root meansquare residual=0.045. The factor GSE explained almosthalf or over half of the variance of each item (0.45–0.75,p-values<0.001).Conclusions The GSE scale is a valid and reliable scalethat can be used to assess general self-efficacy in patientsundergoing bariatric surgery.