Introduction. Internet-based psychological interventions are an effective option for treating mental health problems. Identifying the acceptability of these services makes it possible to improve their design and user adherence. However, only a few psychometric instruments exist to evaluate this acceptability. Objective. To design and evaluate the psychometric properties of an internet-based psychological interventions questionnaire, based on the theory of technology acceptance. Method. The study was divided into three parts: 1) Design of instrument items, 2) analysis of psychometric properties and exploratory factor analysis, and 3) confirmatory factor analysis. Results. The instrument proved to have adequate psychometric properties, with the following goodness-of-fit measurements: χ2/df = 168.92/74 = 2.28, CFI = .935, TLI = .920, RMSEA = .080, 95% CI [.64, .096]. The analysis of internal consistency found an α = .91 for the total scale, an α = .91 for the first factor, “Approval of use,” an α = .79 for the second factor, “Perceived usefulness,” and an α = .59 for the third factor, “Perceived risk.” Discussion and conclusion. The evaluation of factors associated with greater acceptability is a potential tool for improving awareness of the use of online psychological interventions.