The previously developed and well-demonstrated mineral saturation geothermometry method is revisited with the objective to ease its application, and to improve the prediction of geothermal reservoir temperatures using full and integrated chemical analyses of geothermal fluids. Reservoir temperatures are estimated by assessing numerically the clustering of mineral saturation indices computed as a function of temperature. The reconstruction of the deep geothermal fluid compositions, and geothermometry computations, are implemented into one stand-alone program, allowing unknown or poorly constrained input parameters to be estimated by numerical optimization using existing parameter estimation software. The geothermometry system is tested with geothermal waters from previous studies, and with fluids at various degrees of fluid–rock chemical equilibrium obtained from laboratory experiments and reactive transport simulations. Such an integrated geothermometry approach presents advantages over classical geothermometers for fluids that have not fully equilibrated with reservoir minerals and/or that have been subject to processes such as dilution and gas loss.