Thiamethoxam is a neonicotinoid, with systemic and contact action, used in Mexico for the care of different traditional fruit crops, mainly in the cultivation of papaya. International organizations such as the EPA (Environmental Protection Agency) and the EFSA (European Food Safety Authority) establish maximum permissible limits of 0.4 mg/kg and 0.05 mg/kg of thiamethoxam in papaya. The aim of this study was to determine the presence and concentration of thiamethoxam in soil and water in papaya crops associated with watermelon from the central area of Veracruz, Mexico. A diagnosis of thiamethoxam management in different soil types of the region was made; through an experimental plot where soil and water samples were taken in the different stages of papaya cultivation associated with watermelon, using HPLC-UV equipment for its determination. The design was random blocks with six repetitions and the software used for data analysis was the Statistica 2007 program. Thiamethoxam was concentrated in amounts of ≥0.40 mg/L in 79% of the samples in water and ≥0.55 mg/kg in 75% of the samples in soil. The highest values of thiamethoxam in soil were in the stage of watermelon culture with 0.4 mg/kg and in the soil preparation of the papaya crop with concentrations of 0.8 mg/kg. Whereas irrigation water from the watermelon cultivation and the soil preparation for the papaya showed concentrations of 0.5 and 0.7 mg/L respectively. The presence of thiamethoxam was identified in 100% of the samples analyzed in the papaya soil preparation stage. The values of the concentrations in soil and irrigation water exceeded the maximum limits established by international standards.