A cost effective green synthesis was adopted to synthesize the cerium dioxide (CeO2) nanoparticles (NPs) using leaf extract of Azadirachta indica plant as reducing agent for thermal and photo catalytic processes. The composition and surface properties of green synthesized CeO2 NPs were determined by observing the elemental analysis and X-ray photoelectron spectroscopy (XPS). The thermal catalytic activity of green synthesized CeO2 NPs toward the decomposition of ammonium perchlorate (AP) was comprehensively demonstrated by differential scanning calorimetry and thermogravimetry analysis techniques. The addition of green synthesized CeO2 NPs in AP showed a significant drop in decomposition temperature of AP by 130 degrees C and reduction in activation energy of pure AP, indicating excellent thermal catalytic behavior of CeO2 NPs. Photocatalytic activity was examined by performing the Rhodamine B dye photodegradation and observed that the green synthesized CeO2 NPs exhibited the good degradation rate of 96% within 120 min. (C) 2017 Elsevier Ltd. All rights reserved.