Purpose – This research extends the theory of planned behaviour (TPB) and aims to study the underlying factors that influence Chinese consumers’ purchase intentions towards green products. The conceptual model encompasses four elements (subjective norms, perceived behaviour control, moral norms and attitude) and one consumer response (purchase intention). Design/methodology/approach – The current research employs a questionnaire survey and two experiments. In Study 1, the hypotheses were tested using structural equation modelling with 485 consumers in China. Study 2 employed a single-factor, two-condition (morally engaged vs control), between-subject design. Findings – The findings reveal that the morally extended TPB framework is more applicable in predicting Chinese consumers’ green purchase intentions than the original TPB model. Attitude plays the most significant role in predicting purchase intentions, and moral norms prove to be a mediator of the relationship between the original construct of subjective norms and purchase intentions. The findings further revealed that moral norms comprise the underlying mechanism of the relationship between subjective norms and attitude. Originality/value – This study therefore expands the TPB theory by including moral norms. Moreover, it contributes to the literature by clarifying the direct, indirect and total effects of each TPB element on the purchase intentions towards green products. Finally, managerial implications are given.