Emotional disorders (ED) (depression and anxiety disorders) are highly prevalent. Currently, there is evidence showing the efficacy of disorder- specific cognitive-behavior therapy (CBT) for ED. However, high comorbidity rates among ED has led some researchers to shift the focus to treatment strategies that might be more widely effective across these diverse conditions (trans- diagnostic approach). Another important line of research in the literature is In- ternet-based psychotherapy. An increasing number of meta-analyses have shown the efficacy and effectiveness of Internet-based CBT treatment protocols for ED. Nevetherless, little is known about the acceptability (i. e. expectations and opinion of treatment) of these types of interventions. We have developed a transdiagnostic treatment protocol and have adapted it so that it can be applied over the Internet. The aim of this study is to describe the protocol and to present data about the acceptability of the online intervention by a sample of patients from a randomized controlled trial (RCT) that we are currently conducting in Spanish public mental health care settings.