Adsorption behavior of urea on silver electrode and the influence of thiourea on its adsorption in snlphuric acid solution were illvestigated by polarization curves and Surface Enhanccd Raman Spectroscopy. Urea was found to undergo a condensation reaction on roughcned silvcr electrode. Billret was the condensation compound, and was adsorbed in the protonatcd forrn on the silver surface. Obvious synergistic mechanism between thiourea and protonated biuret was proposed. Adsorption behavior of urea on silver electrode and the influence of thiourea on its adsorption in snlphuric acid solution were illvestigated by polarization curves and Surface Enhancd Raman Spectroscopy. Urea was found to undergo a condensation reaction on roughcned silvcr electrode. Billret was the condensation compound, and was adsorbed in the protonatcd forrn on the silver surface. Obvious synergistic mechanism between thiourea and protonated biuret was proposed.