The Cu-Sn alloy coatings were synthesized on 27SiMn steel by direct current (DC), pulse current (PC) and pulse reverse current (PRC) electrodeposition techniques from pyrophosphate-based electrolyte. The hydrogen permeation behaviors during the electrodeposition by different techniques were investigated using Devanathan-Stachurski method. The results demonstrated that the hydrogen permeation amount of different electrodeposition techniques decreased in the order: DC > PC > PRC. Frequency and duty cycle have great effect on the sub-surface concentration C-o of atomic hydrogen and hydrogen permeation amount. The minimum of hydrogen permeation amount was observed at the frequency of 1000 Hz or 2500 Hz and the duty cycle of 40%. It indicates that the amount of permeated hydrogen in the steel during deposition can be reduced due to the decrease of C-o by PC and PRC methods. (C) 2009 Elsevier Ltd. All rights reserved.