A mathematical procedure for analyzing decay curves, based on the least-square method, was developed and the analysis of the two-component curve was presented as an example. The precision of the method was evaluated depending on the following factors: total time of measuring the curve, number of experimental points, representation of individual components, and ratio between half-lives. The method is capable to resolve individual activities even in the case of unfavourable half-life ratios, as e.g. for mixtures42K +24Na.