AbstractThe program SOL1, written in Turbo‐PASCAL for use on a personal computers (IBM‐PC or compatible), has been developed for calculating the equilibrium concentrations of the species in the multicomponent ligand–metal mixtures of up to 21 components and 150 species. The main features are the easy data input system, the possibility of three different tasks (calculating the composition of a single solution, simulating titration curves and calculating the species distribution as a function of pH) and procedures for drawing the calculated curves on Roland DXY plotters. The program has been tested by a study of six different complex sy