A selective catalytic reduction process with a palladium catalyst for reducing NOx in a gas, using hydrogen as a reducing agent. A zirconium sulfate (ZrO2)SO4 catalyst support material with about 0.01-2.0 wt. % Pd is applied to a catalytic bed positioned in a flow of exhaust gas at about 70-200° C. The support material may be (ZrO2—SiO2)SO4. H2O and hydrogen may be injected into the exhaust gas upstream of the catalyst to a concentration of about 15-23 vol. % H2O and a molar ratio for H2/NOx in the range of 10-100. A hydrogen-containing fuel may be synthesized in an Integrated Gasification Combined Cycle power plant for combustion in a gas turbine to produce the exhaust gas flow. A portion of the fuel may be diverted for the hydrogen injection.