A loading-controlled Ag/C foam catalyst prepared by facile electrochemical growth in an environmentally friendly electrolyte with 5,5-dimethylhydantoin (DMH) and niacin (NA) as complexing agents is reported. By controlling the cathodic current density and the growth time, the loading amount of silver on carbon support can be easily controlled. Ag/C foam catalyst with small size, ideal distribution, and controllable loading amount of Ag particles can be obtained on foam carbon support.