A novel approach to formation of a mercury film electrode (MFE) at the surface of a carbon paste electrode is proposed in this paper. This MFE is easy to fabricate, has good reproducibility and avoids the use of a plating mercury solution. In this new type of MFE, mercuric diethyldithiocarbamate (Hg(DDTC)2) was mixed with graphite powder and paraffin oil to form a chemically modified carbon paste electrode. When a -0.95 V potential was applied to the electrode, the Hg(II) (in Hg(DDTC)2) was reduced to metallic Hg, thus forming a mercury film at the surface of the carbon paste electrode. The characteristics of this MFE were studied. This modified electrode was used in anodic stripping voltammetry. Conditions for the simultaneous determination of trace amount of Pb(II) and Cd(II) were also investigated.