Abstract This report allowed the detection of three substances using a carbon paste decorated with MoO 2 (MoO/CPE). Tartrazine (TZ), sunset yellow (SY) and thiomersal (TMS) were analyzed for adsorptive voltammetry. The electrode was characterized by scanning electron microscopy, energy dispersive spectroscopy and cyclic voltammetry. TZ, SY and TMS were observed at 1.07, 0.80 and 0.95 V respectively. The detection limits (3*σ/m) for TZ, SY and TMS were 0.04, 0.06 and 0.10 μmol/L, respectively. The new analytical method was applied using pharmaceutical samples.