In the present study Ultrasonic velocity (u), density (ρ) and viscosity (η) have been measured at 2 MHz frequency in the binary mixtures of thiamin hydrochloride with NaOH in the concentration range (0 to 0.1 M) at 303K using ultrasonic interferometer technique. The measured value of ultrasonic velocity, density and viscosity have been used to estimate the acoustical parameters namely adiabatic compressibility (βa), relaxation time (τ), acoustic impedance (z), free length (Lf), free volume (Vf) and internal pressure (Pi) , with a view to investigate the nature and strength of molecular interaction in the binary mixture of thiamin hydrochloride with NaOH. The obtained result support the occurrence of Complex formation through intermolecular ionic bonding in these binary liquid mixtures