Experimental solubilities of 7-chloro-2-methylamino-5-phenyl-3H-1,4-benzodiazepine-4-oxide, (chlordiazepoxide), 7-chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one (diazepam), and 7-chloro-5-(2-chlorophenyl)-3-hydroxy-1,3-dihydro-1,4-benzodiazepin-2-one (lorazepam) in (propane-1,2-diol + water) at T = 303.2 K were reported. The Solubility of drugs increased with the addition of propane-1,2-diol and reached the maximum values in pure propane-1,2-diol. The Jouyban-Acree model was used to fit the experimental data, and the Solubilities were reproduced using a previously trained version of the Jouyban-Acree model and the Solubility data in monosolvents in which the overall mean relative deviations (OMRDs) of the back-calculated and predicted Values with the corresponding experimental data were 4.2 % and 10.7 %. The Solubilities of the three drugs were also predicted using a trained version of the log-linear model of Yalkowsky, and the OMRD was 21.1 %.