Pesticides are toxic chemicals or mixtures of substances that are intentionally released into the environment to prevent, control and/or kill pest populations. Uncontrolled use and resistance of pesticides to biological, chemical and photolytic degradation methods cause their accumulation in the environment with negative consequences for flora and fauna and human health. The aim of this study is to define optimal operating conditions for photocatalytic degradation of the insecticide model component. As a model component, the insecticide acetamiprid (C10H11CIN4) was used, which is an integral component of the product Mospilan (Genera) with a content of 20% by weight. The research was carried out in a double-walled annular-type boiler reactor and recirculation of the reaction mixture. Four different photocatalysts in suspended form were used. The influence of radiation sources (excitation), mass and type of photocatalyst, pH value and initial concentration of acetamiprid solution on the degradation rate of acetamiprid was investigated. The efficiency of the photolytic and photocatalytic degradation reactions was monitored by determining the change in acetamiprid concentration. A comparison of the photolytic and photocatalytic decomposition reactions of acetamiprid under different reaction conditions was performed and conclusions were drawn about the efficiency of the process. The reactor model and kinetic model were proposed, the model acceptability was evaluated and the model parameters were estimated.