Chemical contamination of groundwater is typically associated with multicomponent solutions, the migration of which is affected by preferential adsorption and solution reactions. Transport models should, therefore, account for advection and dispersion and for the reactions in the solution and on the solid phase. The two-dimensional model METLI has been developed for the personal computer (PC) simulation of groundwater transport with competitive adsorption of a three-species system consisting of a metal, a ligand, and their dominant complex at a given pH. The model structure, which employs spatial and process splitting algorithms, is described. One- and two-dimensional application examples are used to demonstrate how chemical reactivity and affinity for adsorption of a species, adsorption capacity of soil, and the number of the adsorbing species affect pollutant plumes in groundwater. The model executes rapidly in PCs using grids of several hundred nodes. ¿ American Geophysical Union 1993