The experimental values of density (rho), speed of sound (u), absolute viscosity (eta) and refractive index (n(D)) properties are reported for aqueous solutions of thiamine hydrochloride (vitamin B-1 center dot HCl) and pyridoxine hydrochloride (vitamin B-6 center dot HCl) within the concentration range (0.01 to 0.55) mol . kg(-1) at three different temperatures, viz. T/K = 278.15, 288.15, and 298.15. Using experimental data, different derived parameters such as the apparent molar volume of solute (phi(V)), isentropic compressibility of solution (beta(S)), apparent molar isentropic compressibility of solute (phi(KS)) and relative viscosity of solution (eta(r)) have been computed. The limiting values of apparent molar volume (phi(0)(V)) and apparent molar isentropic compressibility (phi(0)(KS)) have been obtained. The limiting apparent molar expansivity (phi(0)(E)) of solute, coefficient of thermal expansion (alpha*) and hydration numbers (n(h)) of above vitamins in the aqueous medium have also been estimated. The experimental values of relative viscosity are used to calculate the Jones-Dole equation viscosity A and B coefficients for the hydrochlorides. The temperature coefficients of B i.e. (dB/dT) for these solutes have been used to study water structure making and breaking effects due to cations. Further, a discussion is made on the basis of solute-solute and solute-solvent interactions. (C) 2012 Elsevier Ltd. All rights reserved.