Although inhibitor adsorption and inhibition mechanisms have been studied extensively using various electrochemical techniques, these electrochemical techniques only provide an indirect estimate of inhibitor adsorption. In the present study, a QCM with dissipation monitoring (QCM-D) was used to investigate the adsorption on gold coated quartz crystal resonator (QCR) of a model corrosion inhibitor (CI) compound at different bulk inhibitor concentrations. In a first step, the classical Sauerbrey’s equation was used to analyze the normalized frequency change data for estimation of adsorbed mass. Normalized frequency change was also analyzed in conjunction with dissipation change using small load approximation (SLA) model to establish the nature of adsorbed layer and to qualify the validity of Sauerbrey’s equation. In context of the bulk inhibitor concentrations tested (50 ppm(w) and 100 ppm(w) of CI in 1wt.% NaCl solution) in this study, the adsorbed layer behaves as a rigid mass. A conscious effort is made to state and validate the assumptions for the analysis of experimental results.