New catalysts for liquid phase nitrate reduction were recently synthesized using multiwalled carbon nanotubes as a support. The most promising catalyst (1%Pd-1%Cu/CNT) was used in this kinetic study. The catalyst experimentally showed high selectivity to nitrogen, between 80 and 89%. A mechanistic model was applied to experimental data to show that the reason for high selectivity is due to the enhanced mass transfer near the catalyst surface promoted by the use of a structured support. The experimental selectivity is close to the maximum selectivity predicted for this catalytic system at the best operating conditions and in the absence of any mass transfer limitations.