We have demonstrated a simple and softer fabrication technique of preparing hollow silica nanoparticles (HSNPs) immobilizing an enzyme catalase within its cavity using calcium phosphate nanoparticles as template. Morphology of the so-synthesized nanoparticles is discussed in the light of dynamic light scattering and high resolution transmission electron microscopy. The average diameter of the particles is about 50 nm. Variation of its activity over a wide range of temperature, pH and a comparison of complete enzyme kinetic study of the entrapped enzyme within the cavity of HSNPs with that of free enzyme in aqueous phosphate buffer solution are vividly discussed.