This article describes the thermodynamic and solution properties of amphiphlic drug Cetirizine HCl in the temperature range of 20-50 °C in aqueous solution. Densities, conductivities, viscosities and surface tension were measured to calculate critical micelle concentration (cmc) and in this way its surface and bulk properties have been estimated.  Various fundamental parameters such as area per molecule at air/water interface and surface excess concentration have been calculated and thermodynamics of micellization has been monitored. Our results show that Cetirizine HCl micellises through closed association process and micellization is found to be entropy driven.  The solution viscosities have been used to estimate the micellar density, partial specific volume and Intermicellar interaction parameter, KH of micelle over temperature range of 20-50 °C. From cmc we have calculated ?Hmic, ?Gmic and ?Smic