Calibration surfaces describing the kinetics of Al/F complex formation are used to develop a linear programming procedure with which the distribution of aluminium species in various solutions is investigated. Samples tested include prepared solutions containing different levels and ratios of hydroxide, fluoride, sulfate, citrate and a fulvic acid, and solutions from soil water extracts and lysimeter water. The results show that the calibration surfaces are robust for describing all the cases tested. Results obtained with fulvic acid solutions agree with reported data on aluminium/fulvic acid complexes. The results obtained with soil solutions are internally consistent and in line with the expected behaviour of humic materials. A software package is described for combining potentiometry with a fluoride-selective electrode with linear programming routines in order to solve problems of aluminium speciation in solutions containing ligands which have unknown thermodynamic characteristics and may be colloidal polyelectrolytes.