A surface wettability measurement method for determining the surface wettability of a surface for operations that require the removal of oil-based fluid such as cementing operations in an oil/gas environment. Time domain reflectometry (TDR) measurements are used to measure the wettability in a wellbore downhole during operations or in a lab environment when fluid flow is present. A surface wettability measurement system for determining the surface wettability of a surface located either in a wellbore downhole or in a laboratory setting using time domain reflectometry for measurements during operations when fluid flow is present.