The equilibrium and kinetic stages of simazine adsorption by humic acids extracted from leached chernozem, brown coal, acidic brown coal, peat, and sapropel at different pH and temperatures are studied. The adsorption capacities of humic acids differ depending on their structure and properties. Simazine adsorption by humic acids is strongly pH-dependent. Temperature has only an insignificant effect on simazine adsorption.