The fabrication and evaluation of a disposable copper mini-sensor ex situ modified bismuth film for the sensing of lead(II) and cadmium(II) via square-wave anodic stripping voltammetry (SWASV) is presented.The sensor was ex situ modified with a bismuth film via electro-deposition through applying a potential of À0.18 V vs. Ag/AgCl (3.0 mol L À1 KCl) for 200 seconds in a 0.02 mol L À1 Bi(NO 3 ) 3 , 0.15 mol L À1 sodium citrate in 1.5 mol L À1 HCl solution. Under the optimal experimental conditions, the voltammetric response was linearly dependent on the analyte concentrations over the range from 1.3 Â 10 À6 to 1.3 Â 10 À5 mol L À1 and from 9.9 Â 10 À7 to 1.2 Â 10 À5 mol L À1 with a limit of detection of 8.3 Â 10 À7 mol L À1 and 5.3 Â 10 À7 mol L À1 for Pb(II) and Cd(II), respectively. The determination of both toxic metallic species was carried out in natural waters using the sensor obtaining results which are in close agreement with those obtained using Flame Atomic Absorption Spectrometry at a 95% confidence level.