A microwave characterization method for on-chip liquid film dielectric property measurement is developed. Microstrip-line based on-chip test structures are fabricated to characterize the microwave dielectric properties of various on-chip liquid films: DI water and binary mixtures of DI water with glucose and ethanol. The obtained microwave dielectric properties are presented in Cole-Cole diagrams, which show general frequency dependence similar to that of bulk liquids. Different concentration levels of glucose and ethanol show different microwave dielectric responses. Therefore, on-chip microwave dielectric spectroscopy provides a promising and inexpensive on-chip sensing mechanism for biomedical and chemical applications.