Background Chronic rheumatic diseases are painful conditions which are not entirely controllable and can place high emotional demands on individuals. Increasing evidence has shown that emotion regulation in terms of actively processing and expressing disease-related emotions are likely to promote positive adjustment in patients with chronic diseases. The Emotional Approach Coping Scale (EAC) measures active attempts to acknowledge, understand, and express emotions. Although tested in other clinical samples, the EAC has not been validated for patients with rheumatic diseases. This study evaluated the data quality, internal consistency reliability, validity and responsiveness of the Norwegian version of the EAC for this group of patients. Methods 220 patients with different rheumatic diseases were included in a cross-sectional study in which data quality and internal consistency were assessed. Construct validity was assessed through comparisons with the Brief Approach/Avoidance Coping Questionnaire (BACQ) and the General Health Questionnaire (GHQ-20). Responsiveness was tested in a longitudinal pretest-posttest study of two different coping interventions, the Vitality Training Program (VTP) and a Self-Management Program (SMP). Results The EAC had low levels of missing data. Results from principal component analysis supported two subscales, Emotional Expression and Emotional Processing, which had high Cronbach's alphas of 0.90 and 0.92, respectively. The EAC had correlations with approach-oriented items in the BACQ in the range 0.17-0.50. The EAC Expression scale had a significant negative correlation with the GHQ-20 of -0.13. As hypothesized, participation in the VTP significantly improved EAC scores, indicating responsiveness to change. Conclusion The EAC is an acceptable and valid instrument for measuring emotional processing and expression in patients with rheumatic diseases. The EAC scales were responsive to change in an intervention designed to promote emotion regulation. The instrument has not yet been tested for test-retest reliability, which is recommended in future studies.