Herein, electroless Pd deposited on Ni-P surfaces using formic acid (FA) as a reducing agent was investigated. Open circuit potential with time (OCPT) and cyclic voltammetry (CV) results suggest that electroless Pd deposited on Ni-P surfaces occurs by a two stage reaction. First, Pd plating proceeds via a galvanic displacement reaction between Ni and Pd2+. Subsequently, Pd deposited via autocatalytic reaction takes place on Pd surfaces. When the displacement reaction was prevented, the autocatalytic deposition of palladium was incapable of proceeding; therefore, it is confirmed that the displacement reaction is a necessary prerequisite for occurrence of the autocatalytic reaction. (C) The Author(s) 2016. Published by ECS. All rights reserved.