Pd-TiO₂ catalysts with five Pd loadings were synthesized using a flame aerosol reactor. Their initial and changed catalytic properties and kinetic characteristics during/for O₂ removal with CH₄ were investigated. Different Pd loadings affected the size of Pd sub-nano clusters/nanoparticles and the speciation fraction of Pd (metallic Pd, PdO and PdO_x (0〈x〈1)). Increased size of Pd nanoparticles on catalysts’ surface due to sintering and the reduction of PdO to metallic Pd or/and PdO_x were observed during the reaction. Fractions of the total surface area of Pd species were calculated, and correlations to the apparent reaction rate constants were established. Apparent kinetic constants were linearly proportional to fractions of total surface areas of metallic Pd or/and reduced Pd oxide were revealed, representing the intrinsic active site. The linear correlation between the O₂ reaction rate and the CO₂ concentration in the initial gas stream was also observed due to an autocatalytic reaction effect.