In the present study, attempt was made to develop photo catalytic process for degradation of phenol with CSTR using ZnO–bentonite clay nanocomposite in presence of UV light. Various process parameters such as effect of pH and flow rate are evaluated while a mechanistic pathway is proposed for the degradation of phenol using LC–MS analysis. Such a green chemistry approach may lead to the designing of future remediation technologies for removal hazardous pollutants from waste water.