A voltammetric method for fast and high sensitive determination of betamethasone (BM) using an amalgam film silver based electrode (Hg(Ag) FE) was developed. Cyclic voltammetry study revealed that the BM reduction process is diffusion controlled with the participation of two electrons and two protons. In the optimum conditions, calibration curve was linear for BM in the concentration range from 5.10(-9) mol L-1 (1.96.10(-6) g L-1) to 0.8.10(-6) mol L-1 (3.14.10(-4) g L-1), with a detection limit of 1.6.10(-9) mol L-1 for preconcentration time of 45 s. Repeatability of method was determined as RSD % for betamethasone concentration of 0.1.10(-7) mol L-1 as 2.1% (n = 5). The proposed method was successfully applied and validated by studying the recovery of betamethasone in commercially available drugs. (C) 2018 The Electrochemical Society.