The sorption and desorption of pesticides in soils may be affected by the addition of char due to crop residue burning in agricultural fields. In this study, sorption and desorption characteristics of atrazine in two soils in the presence and absence of a char were evaluated. Wheat (Triticum aestivum L.) char and two soils (Hartsells and Grady) of different organic carbon contents and mineralogy were used. The sorption isotherms for the two soils were highly linear within the tested concentration range, suggesting that partitioning into organic matter was the primary sorption mechanism. The Freudlich model parameters for Hartsells (K_f =1.29 and n =0.98) and Grady (K_f =2.04 and n =0.91) indicate that the sorption capacity of Grady was slightly higher than that of Hartsells, which can be attributed to the higher organic matter content of the former soil. The isotherms for the char amended soils showed an increased nonlinearity and sorption capacity. The 1% char amendment in both soils produced similar isotherms indicating that the presence of a small amount of char in soils dominated overall sorption processes. The amount of atrazine sorbed by char was much higher than that by both soils. A dual-mode model predicted sorption by char better than the Freundlich or Langmuir model. The equilibrium desorption experiments indicated hysteresis in Hartsells soil and char but not in Grady soil. With char amendment, both soils exhibited hysteresis. The fraction resistant to desorption was 50% in both soils under the experimental conditions. The addition of char to soils increased the resistant fraction to 70% which was the same as that in char. The results suggest that the presence of char in soils controls the sorption and desorption processes and thus ultimately affects the environmental fate of pesticides.