Anxiety Disorders are one of the most prevalent psychological problems around the world and if not treated they tend to become chronic. Cognitive Behavioral Therapy (CBT) is the treatment of choice, being the component of in vivo exposure (IVE) the central feature. Despite its efficacy it is still a hard component to implement for the patients. Information and Communication Technologies (ICT) can help assisting and/or applying psychological interventions. The proposed study will fill the existing gap in this sense as it will assess the efficacy of a fully configurable, sensor-guided and location-based (GPS) app for the in vivo exposure component. It will also address the shortage of clinical validation studies of mHealth apps thanks to the proposed RCT. The study will expand our knowledge about the use of technologies in mental health problems and help improve the effectiveness of exposure therapy.