Organic-inorganic composites were prepared as colloidal particles of a cross-linked, thermally responsive polymer. Hybrid PNIPAM-polysiloxane particles and composite polymeric particles with embedded nanoparticles of an inorganic metal-oxide (MOx) such as CeO2 and TiO2 were formed. To promote the incorporation of unaggregated nanoparticles, temperature responsive microspherical gels (microgels) of N-isopropylacrylamide (NIPAM) with interpenetrating (IP) linear chains of poly(acrylic acid) (PAA) were used. The organic-inorganic composition of the hybrid polymer network was controlled by changing the time for condensation and hydrolysis of the siloxane monomer during synthesis. Experimental results indicated that the planarization of silicon oxide wafers using these hybrid particles and composites exhibited lower topographical variations and surface roughness as compared to slurries consisting of only silica or ceria nanoparticles while achieving similar removal rates and better or similar frictional characteristics.