Acidic herbicides can exist in different proportions of neutral and anionic forms in soil, depending on pH value, and the anionic form behaves differently from the nonionic molecule, severely limiting generalizations. Weed control efficacy and environmental behavior of herbicides depend on sorption. Among the models frequently used in predicting environmental behavior and fate of pesticides, only a few have an option for acidic herbicides. In this chapter, recent findings on modeling pH-dependent sorption of monovalent acidic herbicides are presented and discussed, aiming to improve technologies for agricultural and environmental purposes. A case study of calculating sorption of monovalent acidic herbicides along with a technology for the estimation of surface runoff and leaching in soil is provided.