Para-nitrophenol (PNP) is a toxic compound widely used in various industries. The release of PNP into the environment not only threatens human health but the ecosystem. Hence, the treatment of contaminated water is necessary. Periodate (PI) is a new oxidant which is used for the generation of free radicals. In the current work, PI was concurrently activated by ultraviolet (UV) and ultrasound (US) to eliminate PNP from aqueous solution. The effects of operating parameters were studied and complete degradation of PNP was obtained in 30min. The presence of ferrous ions increased the PNP degradation rate. Scavenging experiments confirmed that HO• and IO3 • were corresponding agents of the PNP degradation, which the latter had a bold role. The performance of PI/UV/US was examined on real wastewater and the results showed that 70% of total phenol was removed during 60min. The PNP degradation intermediate was recognized and a pathway of PNP degradation was proposed. Although PI/UV/US process is high energy consuming, its excellent performance can be a rational reason for the scaling up the process.