The discipline of operations management (OM) has long been offering differing quantitative techniques for improving the efficiency of banking operations. However, there has been a trend in recent years that operations and services of the banking industry are becoming more diverse and unstructured, rendering many traditional OM quantitative techniques less effective in performance improvement. By integrating the literature on banking operations, service quality, leadership style and work teams, we argue that leadership style and team performance are crucial concerns determining the service quality performance of today's banking operations in a team setting. Using data collected from 192 employees from 32 operational teams (a leader and five members in each team) in 15 retail banks in Macau, China, we investigated whether the five dimensions of transformational leadership have an impact on team performance with respect to team cohesion, team leader job satisfaction and team competence; and whether the dimensions of team performance have an impact on such service quality dimensions as reliability and responsiveness. We found that one of the dimensions of transformational leadership and two of the dimensions of team performance have a significant impact on service quality. We discuss the implications of the findings for research and practise. ► Aim: How transformational leadership and team performance impact service quality. ► Data: Surveyed 192 employees of 32 operational banking teams. ► Finding: Intellectual stimulation impacts service quality through team performance. ► Conclusion: Intellectual stimulation is the most important leadership dimension.