Quantitative structure-property relationship (QSPR) modeling of the stability constant logK of the 1:1 (M:L) complexes of 6 transition-metal cations (M) with 261 (Mn2+), 87 (Fe2+), 105 (Y3+), 186 (La3+), 226 (Pb2+), and 66 (UO22+) organic ligands (L) in aqueous solutions at 298 K and an ionic strength 0.1 M was performed using ensemble multiple linear regression analysis and substructural molecular fragments as descriptors. The models have been validated in external 5-fold cross-validations procedure and on new ligands recently reported in the literature. Predicted logK values were calculated by consensus models as arithmetic means of 315 (Mn2+), 119 (Fe2+), 260 (Y3+), 290 (La3+), 304 (Pb2+), and 249 (UO22+) individual models. Absolute prediction error of logK is below 1.0 for 75% (UO22+), 70% (Mn2+, Fe2+, La3+), 6596 (Pb2+), and 60% (Y3+) of the ligands and comparable with the systematic errors in experimental data. The developed QSPR models were used to screen selective ligands for the studied cations. The obtained models are incorporated in the COMET predictor available at http://infochim.u-strasbg.fr/cgi-bin/predictor.cgi.