A new voltammetric method of hydrocortisone (HC) determination using renewable mercury film electrode is presented. The electrode mechanism reaction of HC was studied and the influence of instrumental parameters such as preconcentration potential and time, pulse height, step potential and supporting electrolyte composition were examined. A linear voltammetric response was obtained for analyte in the concentration range from 0.02.10(-6) mol L-1 (7.25.10(-6) g L-1) to 1.2.10(-6) mol L-1 (0.44.10(-3) g L-1), with a detection limit of 4.8.10(-9) mol L-1 for preconcentration time of 30 s. Repeatability of method was determined as RSD % for hydrocortisone concentration of 0.2.10(-6) mol L-1 as 4.6 % (n = 9). The proposed method was successfully applied and validated by studying the recovery of hydrocortisone in pharmaceutical products. (C) 2015 Elsevier Ltd. All rights reserved.