The mixed micelles constituted by a nonionic surfactant widely used in the biochemical field, n-octyl-beta-D-glucopyranoside, and a cationic surfactant with 12 carbon atoms on the hydrophobic tail, dodecyltrimethylammonium bromide, have been studied in aqueous solution, at 298.15 K, by means of conductivity, speed of sound, density, and fluorescence spectroscopy experiments. From these data, the monomeric and micellar phases of the mixed aggregates were fully analyzed through the determination of the total and partial critical micellar concentrations, the dissociation degree of the mixed micelle, the total and partial aggregation numbers, the apparent molar volumes and isentropic compressibilities, the hydration numbers, and the corresponding changes in these thermodynamic properties due to the mixed aggregation process. The experimental findings have been compared with those obtained with several theoretical models, some of them modified in this work to take into account the specific characteristics of the aggregates studied herein.