gold disc electrodes of 10 mm diameter were fabricated using gold wires. the underpotential deposition (upd) of lead on gold ultramicrodisks was investigated by cyclic voltammetry and chronoamperometry, using dilute solutions of pb2+ in 0.2 mol dm-3 hclo4. the upd of pb(0) occurs between 0 v and -0.4 v vs. sce. the process of underpotential deposition is controlled by diffusion. the results of voltammetry experiments show that a monolayer of lead is formed in the upd region. the results of the chronoamperometry experiments demostrate that the formation of a complete monolayer can be related to the appearence of a nonmonotonic current-time transient.