The removal of selenium from oil refinery wastewater presents significant challenges for conventional treatment processes. In this study, the efficacy of using freshly produced nanoscale zero-valent iron particles (nZVI) to improve selenium removal from oil refinery wastewater was investigated. The treatment process was also evaluated in combination with electrochemical peroxidation (ECP). The parameters evaluated were treatment time, Fe/Se molar ratio and electric current density (when using ECP). The results showed that for this specific wastewater, the use of freshly produced nZVI with a low degree of oxidation led to more effective selenium removal without ECP. Under the studied conditions, the highest selenium removal efficiency (90.2%) was achieved at a Fe/Se molar ratio of 3800 and a treatment time of 90 min. This approach was found to be the most cost-effective while complying with the regulatory wastewater discharge limit.