In this study, dissolution behaviour of 1,2,4-thiadiazole derivative (1-[5-(3-chloro-phenylamino)-1,2,4-thiadiazol-3-yl]-propan-2-ol) displaying an anti-Alzheimer activity was examined in biorelevant media such as Simulated Gastric Fluid (SGF, pH 1.2), Fasted State Simulated Gastric Fluid (FaSSGF, pH 1.6) and Fasted State Simulated Intestinal Fluid (FaSSIF, pH 6.5). It was found that solubility and dissolution rate of 1,2,4-thiadiazole derivative under consideration are not strongly dependent on pH, whereas these parameters are significantly affected by the buffer composition. Dissolution was found to be more effective in buffers composed of the surfactant micelles. It was demonstrated that considerable increase in solubility and dissolution rate in SGF is achieved through the interaction of 1,2,4-thiadiazole derivative with the micelles of sodium dodecyl sulfate. On the contrary, CMC of sodium taurochalate was shifted in the presence of 1,2,4-thiadiazole derivative, therefore, dissolution process is not so efficient in FaSSIF. Interactions occurring between 1,2,4-thiadiazole derivative and the components of biorelevant media were investigated in detail by means of UV/VIS spectroscopy, ¹H-NMR and phase solubility methods.