There is concern that intra-articular electrosurgical ablation may cause thermal soft tissue damage, particularly chondrolysis, if excessive temperatures are reached. The aim of this study was to determine whether the intra-articular temperature during arthroscopic subacromial decompression using a monopolar electrosurgical ablator remains below a safe level. Data was collected prospectively from consecutive shoulder arthroscopic subacromial decompressions performed at our institution. Shoulder arthroscopy was performed using three standard portals. Evaluation of the glenohumeral joint and subacromial space was performed in a standard manner. Soft tissue resection of the subacromial bursa was performed using a monopolar electrosurgical ablator probe with continuous integral suction. Additional procedures such as acromioclavicular joint excision and rotator cuff debridement or repair were performed as appropriate. Bone resection, if required was performed using an arthroscopic burr. The temperature of the fluid within the shoulder and subacromial space was continuously monitored using a sterile digital temperature probe. The surgeon performing the procedure was blinded the collection of data. Data from thirty subacromial decompressions has been collected. 8 patients had full thickness cuff tears of which 6 were debrided, and 2 repaired arthroscopically. 13 patients had acromioclavicular joint excision. Mean operating time was 46 minutes (30–107). The infusion pressure ranged from 40 to 65 mmHg. The median volume of infused fluid was 3900 ml (1500 to 9000). The starting temperature ranged from 18.3 to 21.9. The mean maximum temperature reached was 27.6 (range 22.7 to 41.8 °C). The results suggest that the intra-articular temperature is maintained within safe levels when a monopolar electrosurgical ablator with integral suction is used to perform soft tissue subacromial decompression.