Effects of K and Pd loading on Co3O4 catalyst for the water gas shift (WGS) reaction were investigated. Pd/K/Co3O4 catalyst showed high and stable activity and high selectivity to WGS. Regarding loading amounts of Pd and K, the latter is important for WGS activity and selectivity. XRD, XAFS, and TPR measurements confirmed potassium loading benefits. Supported Pd promoted oxidation of CO with lattice oxygen. The synergetic effect of these functions of K and Pd protected high catalyst activity and stability.