Stringent regulation is endorsed to restrict global gaseous and particulate vehicle emissions by adapting advanced catalytic systems on the exhaust, incorporating costly platinum group metals (PGM) for oxidation catalysis. Porous silica and alumina particles are synthesized in the present work via a one-step aerosol spray route. The particles are doped with Pt, Ce and Na and are evaluated with respect to their pore size distribution, exhibiting surface areas between 6–269 m2/gr. The particles have been evaluated in a packed bed reactor with respect to NO oxidation in presence or absence of hydrocarbons (C2H4) in order to study the hydrocarbon inhibition effect on oxidation kinetics, showing higher conversion curves for higher surface area samples. The current work studies also the correlation between reactant accessibility to the in-pore Pt nanoparticles and catalytic activity by reaction kinetic model.