Zirconia nanoparticles were synthesized by the non-hydrolytic thermal decomposition of zirconyl chloride octahydrate in the presence of oleylamine and oleic acid. The nanoparticles were characterized by XRD, HR-TEM and EDAX techniques. TEM observation confirmed that the nanoparticles have an approximately spherical shape with an average size of 3–4 nm and a non-monoclinic structure. Unlike previous approaches, our synthesis of the catalytically relevant (tetragonal and/or cubic) phase of this material did not require (i) an annealing step to stabilize the tetragonal phase, or (ii) the inclusion of dopants. Furthermore, these high surface area tetragonal zirconia nanoparticles showed a good catalytic activity towards the Knoevenagel condensation.