A linear bilogarithmic hyperbolic cosine method for evaluating acidity constants of two-step overlapping equilibria (H2R/HR/R) from spectrophotometric measurements, applicable in those cases in which the absorbance versus pH curve passes throughout a maximum or a minimum in the region of pH in which the intermediate species predominates, has been devised in this paper. In order to evaluate its usefulness the method has been applied to five systems previously described in the literature.