Adsorption of PbBr2 complex to the surface of a mercury electrode was measured by pulse and de polarography. Theoretical models were developed and the adsorption parameters were calculated from de polarographic data. The adsorption of PbB2 occurs according to the surface complexation mechanism with strong lateral attractions in the adsorbed layer. The maximum surface concentration of adsorbed PbBr2 is linearly correlated to the surface concentration of initially adsorbed bromide ions. The surface complexation constant is lambda(3) = (7.5 -/+ 1.5) x 10(3) M(-1), Frumkin’s coefficient is approximately g = (4.1 -/+ 0.7) x 10(12) J cm(2) mol(-2), and the maximum coordination factor is (f(3))(-1) = 5.0 -/+ 0.5. Each initially adsorbed bromide ion serves as a center of crystallization for a maximum of five molecules of PbBr2.