Densities rho, have been measured for L-Proline in aqueous Metformin Hydrochloride solutions of (0.05, 0.10, 0.15 and 0.20 M) mol kg(-1) at T = 298.15-318.15 K. Apparent molal volumes V phi have been determined from the experimental densities. These data have been used to calculate several thermodynamical parameters such as standard partial molal volume V phi(0), transfer volume Delta V-tr phi(0), hydration number n(H), the second derivative of infinite dilution of partial molal volume with respect to temperature, viz., partial derivative V-2 phi(0)/partial derivative T-2. Furthermore apparent molar expansibility E-0, thermal expansion coefficient, alpha(2) and the pair and triplet interaction coefficient have been calculated and reported. These results interpreted through a cosphere overlap model indicate the presence of strong solute-co-solute interactions in the reported systems. (C) 2019 Elsevier Ltd.