There are first indications that an Internet-based cognitive therapy (CT) combined with monitoring by text messages (Mobile CT), and minimal therapist support (e-mail and telephone), is an effective approach of prevention of relapse in depression. However, examining the acceptability and adherence to Mobile CT is necessary to understand and increase the efficiency and effectiveness of this approach. Method: In this study we used a subset of a randomized controlled trial on the effectiveness of Mobile CT. A total of 129 remitted patients with at least two previous episodes of depression were available for analyses. All available information on demographic characteristics, the number of finished modules, therapist support uptake (telephone and e-mail), and acceptability perceived by the participants was gathered from automatically derived log data, therapists and participants. Results: Of all 129 participants, 109 (84.5%) participants finished at least one of all eight modules of Mobile CT. Adherence, i.e. the proportion who completed the final module out of those who entered the first module, was 58.7% (64/109). None of the demographic variables studied were related to higher adherence. The total therapist support time per participant that finished at least one module of Mobile CT was 21. min (SD = 17.5). Overall participants rated Mobile CT as an acceptable treatment in terms of difficulty, time spent per module and usefulness. However, one therapist mentioned that some participants experienced difficulties with using multiple CT based challenging techniques. Conclusion: Overall uptake of the intervention and adherence was high with a low time investment of therapists. This might be partially explained by the fact that the intervention was offered with therapist support by telephone (blended) reducing non-adherence and that this high-risk group for depressive relapse started the intervention during remission. Nevertheless, our results indicate Mobile CT as an acceptable and feasible approach to both participants and therapists.