In the psychotherapeutic treatment of social phobia, the hand movement behaviour exhibited during the interaction provides information about the success of the therapy. In particular, the degree of mutual somatosensory stimulation of the hands (hands moving on each other, as a unit, apart) appears to be relevant regarding the patient's mental state. To test this hypothesis, the present study investigates hand coordination in the course of psychotherapy in patients with and without symptom improvement and in the corresponding therapeutic dyads. Forty-two videos of patient–therapist dyads consisting of 21 patients (n = 11 non-improved; n = 10 improved; according to Liebowitz Social Anxiety Scale self-assessment) from the Social Phobia Research Network project were investigated in early psychotherapy sessions and in pre-last sessions. Hand movements of four randomised video sequences per dyad were analysed with NEUROGES^®-ELAN. Patients with non-improved symptoms displayed shorter act apart coordination and more act on each other coordination than patients with improved symptoms. Patients displayed more act apart and act on each other and less act as a unit coordination than therapists. In therapeutic dyads, act on each other coordination in early sessions, as well as short act apart coordination, was significantly related to non-improvement. Patients with non-improved symptoms are characterised by more hand coordination associated with a high degree of somatosensory stimulation serving self-regulation (act on each other), as well as short complex gestural expressions (act apart). Thus, hand coordination constitutes a progression and outcome parameter informing on somatosensory stimulation.