The sudden increase in population and the development of industry lead to increasing pollution of water and other components of the environment. Because of the growing demand for food, it is necessary to provide means to help maintain the quantity and quality of agricultural crops. For this reason, pesticides are being used with increasing frequency. As environmental pollution has reached great proportions, mankind is faced with the challenge of combating both pesticides and other types of pollution. To this end, science and practice are investing utmost efforts in developing advanced oxidation processes, among which photocatalytic decomposition stands out as an innovative solution. Photocatalytic decomposition is a process that, according to experience, is characterized by a high efficiency of degradation of various organic compounds, producing only small amounts of environmentally harmful by-products. In the theoretical part of the paper, some more is said about the pesticides themselves and their harmful effects. In addition, the photocatalytic process using TiO2 as a photocatalyst is presented in detail, with a special emphasis on the process conditions that influence the process itself. The aim of this work was to investigate how certain parameters affect the photodegradation of the neonicotinoid imidacloprid in an aqueous medium. Through statistical design, i.e., the experimental design, the system is set up to change three variables: pH, radiation source, and type of oxidant. In this paper, the experimental procedure, the working conditions and the analytical methods used, as well as the results obtained, are described and supplemented with explanations, graphical representations and tables. At the end, a conclusion is drawn, which is a brief summary of the whole work, and it is shown which parameters have the greatest influence on photodegradation.