This thesis investigated the interfacial behavior of some selected solutions in contact with one surface of Quartz Crystal Microbalance (QCM). A device was constructed to monitor viscosity of solutions using fundamental frequency of 9 MHz and 10 MHz quartz crystal. Piezoelectric quartz crystals with gold electrodes were mounted by O-ring in between liquid flow cell. Only one side of the crystal was exposed to the solutions which were pumped through silicon tube by a peristaltic pump. The measured frequency shift was observed in order to investigate the interfacial behavior of some selected solution in contact with one surface of Quartz Crystal Microbalance (QCM). An analysis of the interaction between an AT-cut quartz crystal microbalance and various liquid system of analytical interest is presented. The analysis which included piezoelectric effects and other influences; liquid properties, experimental conditions and the characteristic of the solution are reported.