The use of liquid chromatography to estimate octanol-water partition coefficients, log k(ow), has been demonstrated. The capacity factor with a mobile phase of 100% water, k(w), has been found to be a useful chromatographic parameter. Values of k(w) were derived from a computer software package (Hipac-G), designed for optimization and simulation of gradient LC systems. The chromatographic parameter, k(w) correlates well with both literature and isocratic LC-generated log k(ow) values. The gradient LC method could be extended to a wider range of test compounds.