In agriculture, the use of pesticides is not only beneficial, but may also have negative consequences on the environment and human health. For this reason, understanding and studying the behavior of these products in different environmental compartments are of paramount importance to evaluate the impact of these pollutants on the environment. Adsorption remains the major phenomenon that controls the behavior of pesticides in soil. The goal of our study is to study the absorption of an extensively insecticide used in Morocco, carbofuran, in the presence of montmorillonite in natural water. The results show that the maximum adsorption of carbofuran is attained within 6 hours. Adapting data of adsorption to isotherms models of Freundlich and Langmuir allowed to deduce the values of the following adsorption parameters (n = 0.526; Kf =0.5) for Freundlich and (kl=6.51; qmax=9.53) for Langmuir. Comparison of linear regression coefficients is in favor of the Freundlich model (r2=0.9633>0.8639). Kinetically, adsorption of carbofuran on montmorillonite follows first- order model. The low retention of carbofuran by montmorillonite may be due to water competition that behaves as the solute to some adsorption sites and/or compensating cations Na+, Ca2+ and Mg2+ present in our sample of natural water, which can saturate the surface sites of the montmorillonite.