The densities, rho, ultrasonic speeds, u and viscosities, eta of the drug isoniazid in water and in aqueous-D-glucose/D-sucrose (5 wt% and 10 wt% glucose/sucrose in water) solvents were measured at temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K and at atmospheric pressure. The rho, u and eta data have been used to calculate apparent molar volumes, V phi, limiting apparent molar volumes, V-phi degrees, apparent molar compressibilities, K-s,K-phi, limiting apparent molar compressibilities, K-s,K-phi degrees, transfer volumes, V-phi,V-tr degrees and transfer compressibilities, K-s,K-phi,K-tr degrees. The viscosity data have been used to determine Falkenhagen Coefficients, A and Jones-Dole coefficients, B. The calculated parameters have been discussed in terms of various solute-solute and solute-solvent interactions prevailing in these solutions. The structure making/breaking ability of isoniazid in these solutions has been examined by using the sign of dB/dT. Furthermore, the Gibbs energies of activation of viscous flow per mole of solvent, Delta mu(1)degrees(#) and per mole of solute, Delta mu(2)degrees(#),enthalpies, Delta H degrees and entropies, Delta S degrees of activation of viscous flow, were also calculated and discussed in terms of transition state theory. (C) 2019 Elsevier Ltd.