The lipophilicity and hydrogen bonding capability of the title compounds was investigated. HPLC lipophilicity indices proved to be appropriate substitutes of directly measured octanol-water partition coef®cients and were used to evaluate the predictive power of 7 different calculative approaches. Conformation effects as well as particularities in the way the triazole and thiadiazolyl-amine moieties are treated by the different calculation systems need to be taken into account in order to establish sound correlations with experimental data. Cyclohexane-water partition coef®cients were determined and used to derive DlogP values as a measure of hydrogen bonding ability. Exploration of the DlogP parameter unraveled particular features of the hydrogen bond capability pattern of the compounds. Thermodynamically derived hydrogen bonding parameters Sc a and Sc d were used for the analysis of all lipophilicity data. A negative contribution of the hydrogen bond acceptor capability, much stronger in the case of the cyclohexanewater partition coef®cients, was found while the hydrogen bond donor factor proved not essential. Similar analysis of the DlogP values revealed a more complex nature of that parameter than being a pure hydrogen bond measure.