This paper reports the effect of aging time for In-Sn co-doped ZnO nanoparticles prepared by simple combustion method. The synthesized nanoparticles were characterized and the detailed characterization confirmed that the prepared nanoparticles are well crystalline. It is observed that an ideal aging time is 24 h. FESEM shows the grain size is of the order of 40-90 nm. Kinetics study reveals the photodegradation of direct red- 31 (DR-31) dye using ZnO nanoparticles as photocatalyst follows first order rate constant. Thus 2 at% of In-Sn co-dopants were used to prepare ZnO nanoparticles. It exhibits the complete degradation of dye only in 120 min under UV irradiation. These unique nanoparticles also played an important role in detecting ethanol gas due to its contribution in facilitating the transport change and augmenting the adsorption quality of target gas molecules. These films have quick response time 120 s while the recovery time was 158 s. (C) 2016 Elsevier Ltd. All rights reserved.