Background: Exercise training is an integral component of evidence-based management programs for many chronic cardiac and respiratory conditions. Despite this, there are limited high-quality studies available on the significance of exercise training in pulmonary hypertension (PH). The aim of this study is to evaluate the short and long-term effectiveness of exercise training in PH patients in terms of exercise capacity, quality of life, cardiac function and disease progression. Methods: This randomized control trial will aim to recruit 50 medically stable PH patients categorised as New York Heart Association functional classification II-III. Participants will be randomly allocated to either the supervised exercise training group or usual care group for the 8-week study period. Exercise training will be conducted in an outpatient setting. Measurements at baseline and following the 8-week study period include exercise capacity (6 min walk distance and cardiopulmonary exercise test), cardiac function (exercise cardiac magnetic resonance imaging [CMRI] and echocardiography), health-related quality of life (Cambridge Pulmonary Hypertension Outcome Review), adverse responses to exercise training and time to clinical worsening. In addition, participants will be followed up for a minimum of 2 year period from commencement of the study so as to monitor long-term clinical outcomes i.e. time to clinical worsening. Discussion: This study will determine whether an 8-week outpatient based supervised exercise training program is safe and beneficial for medically stable PH patients in the short and long term. This will be the first study to examine the impact of exercise training on right heart function using exercise CMRI. Results from the study will contribute new knowledge in relation to the impact of exercise training on cardiac function, long-term prognosis and inform clinical practice guidelines for this patient population. Moreover, the study will add to our understanding regarding the efficacy of exercise training in individuals with PH in an outpatient setting.