A core-shell catalyst supported on the carbon fiber paper was developed for the effective electrocatalytic reduction of concentrated nitric acid (4.0 M). The potential range of cyclic voltammetry deposition was adjusted to investigate the influence of the chemical state of electrodeposited Ir on concentrated nitric acid reduction. The results indicate that a core of Pt with a thin IrO2 shell shows greatly enhanced catalytic activity comparing to the nano-Pt.