Solid-contact Ion Selective Electrodes (SC-ISEs) for the detection of lead have been prepared on screen-printed substrates in order to produce low-cost, disposable sensors for environmental monitoring. The materials used as solid contact layer, the deposition techniques used, and the layer thickness greatly affects the performance of the sensors. Poly(3-octylthiophene-2,5-diyl) (POT) and poly-3,4-ethylenedioxithiophene (PEDOT) have been employed in this investigation. For sensors prepared with POT, the batch reproducibility depends on the amount drop-cast, i.e., thickness. In case of PEDOT which is grown galvanostatically the trend is more complex and batch reproducibility appears to depend on the current density. In the latter case, both the film thickness and both the degree of overoxidation of the polymer appear to influence sensor reproducibility.