The stability of photoluminescence (PL) intensity from chemically etched silicon microparticles is studied. Etched microparticles have many narrow and deep trenches on surface. They show visible orange-red PL, which decreases in intensity during continuous excitation by ultraviolet light. The intensity of PL partially recovers when the surrounding gas is changed from air to nitrogen. Thus PL quenching consists of both reversible and irreversible processes and we propose a kinetic model that consists of two quenching paths. Adsorption and desorption of oxygen followed by irreversible oxidation of emission sites are considered in the fast quenching pathway, while the slow pathway involves transport of oxygen molecules to emission sites in trenches with poor access. Our model agrees well with experimental data and rate constants of involved processes are determined, with which we discuss kinetics in PL quenching. Possible strategy to increase PL stability is also discussed. (C) 2015 Elsevier Ltd. All rights reserved.