Recent research on green human resource management suggests that the social exchange process is conducive to employees behaving pro-environmentally. Previous studies have focused exclusively on reciprocal exchange and have largely overlooked the possibility that negotiated exchange also occurs. In this paper, a research model is developed to test whether the effect of green human resource management on employee eco-initiatives through the mediation of supervisory support for the environment is conditioned by felt responsibility for change and negotiated exchanges. Using data from a two-wave study, the findings show that the mediating effect is stronger at high levels of negotiated exchange only for employees displaying low levels of felt responsibility for change. The results also indicate that negotiated exchanges do not intervene in the case of employees exhibiting high levels of felt responsibility for change. This study provides new insights for understanding how social exchange operates in an environmental sustainability context.