This study examines the purchasing behaviour for environmentally sustainable products using the framework of the Theory of Planned Behaviour. It investigates the determinants of the purchase intention for environmentally sustainable products leading to the purchase behaviour for the same. The data collected for the study was analyzed using Structural Equation Modelling (SEM). The result of the study indicates that environmental knowledge has a significant positive relationship with the attitude towards environmentally sustainable products. The strength of significant relationship between attitude and purchase intention is greater compared to the significant relationship between perceived behavioural control and purchase intention. Subjective norm was not found to be significantly related to purchase intention. A significant positive relationship was also found between purchase intention and purchase behaviour. The study has helped in understanding the relative strength of determinants of purchase intention with regard to environmentally sustainable products which lead to purchase behaviour for the same. The findings have important implications for marketers as well as for policy makers.