This paper examines the relationships among environmental regulations (ER), staff quality (SQ), R&D efficiency (RDE), green technology (GT), and profit. The research sample comprises 1197 firms in 16 manufacturing industries in China, during 2008 and 2015. DEA-based measures are employed to research firm RDEs, and the results show that SQ is essential for high RDE and GT (as expected), but the main effects of SQ are mixed. Importantly, we find that ER moderates the SQ-GT, SQ-RDE and SQ-profit relationships. Specifically, if ERs are eased, SQ is of limited benefit to GT or profit. However, at or above the ER threshold level, firms can improve SQ for further improvements in GT and profit. The implications of our findings on theory and practice are also discussed. •This paper examines the relationships among ER, SQ, RDE, GT, and profit.•The sample comprises 1197 firms in 16 manufacturing industries.•DEA-based measures are employed to research firm RDEs.•SQ is essential for high RDE and GT, but the main effects of SQ are mixed.•ER moderates the SQ-GT, SQ-RDE and SQ-profit relationships.