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The solubility values and thermodynamic parameters of a natural phytomedicine/nutrient piperine (PPN) in Transcutol-HP (THP) + water combinations were determined. The mole fraction solubilities (<i>x</i>_e) of PPN in THP + water combinations were recorded at <i>T</i> = 298.2–318.2 K and <i>p</i> = 0.1 MPa by the shake flask method. Hansen solubility parameters (HSPs) of PPN, pure THP, pure water and THP + water mixtures free of PPN were also computed. The <i>x</i>_e values of PPN were correlated well with “Apelblat, Van’t Hoff, Yalkowsky–Roseman, Jouyban–Acree and Jouyban–Acree–Van’t Hoff” models with root mean square deviations of < 2.0%. The maximum and minimum <i>x</i>_e value of PPN was found in pure THP (9.10 × 10⁻² at <i>T</i> = 318.2 K) and pure water (1.03 × 10⁻⁵ at <i>T</i> = 298.2 K), respectively. In addition, HSP of PPN was observed more closed with that of pure THP. The thermodynamic parameters of PPN were obtained using the activity coefficient model. The results showed an endothermic dissolution of PPN at <i>m</i> = 0.6–1.0 in comparison to other THP + water combinations studied. In addition, PPN dissolution was recorded as entropy-driven at <i>m</i> = 0.8–1.0 compared with other THP + water mixtures evaluated.