Some artificial ponds (APs) are designed to collect part of the agricultural water fluxes and dissipate their pesticide contamination through a synergy of physicochemical processes. As part of a two-paper series, this paper describes the development of PESTIPOND, a process-based model for pesticide fate in AP. PESTIPOND comprises a hydrological model and a pesticide transfer model. A test-case simulation shows that PESTIPOND can predict the mass dynamics of different pesticides within AP compartments. Sensitivity analysis evidenced that adsorption–desorption, biotransformation, and photolysis have the most significant impact on the behavior of dissolved pesticides in APs. PESTIPOND is a promising tool for better understanding the performance of ponds and can help improve AP's efficiency in preserving water quality. A second paper addresses the application of PESTIPOND in a real-case scenario and its validation. The model can thus be integrated into landscape modeling tools (e.g., surface water assessment tools) to predict pesticide transfer at the watershed scale.