A metallocene/MAO-based solid olefin polymerization catalyst has been developed using chemically functionalized nanoparticles (carboxylate-alumoxanes) as a well-defined substrate. Reaction of p-hydroxybenzoate-alumoxane (p-HB-A) nanoparticles, formed from the acid with boehinite, with methylalumoxane (MAO) results in a solid nanoparticle-based MAO (n-MAO), which in combination with zirconocenes [including Cp2ZrCl2, Cp2ZrMe2, and ((BuCp)-Bu-n)(2)ZrCl2] produces an active solid catalyst for olefin polymerization. The catalytic activity of the n-MAO-based catalyst is comparable to the homogeneous analogue and a traditional silica-supported catalyst under identical reaction conditions and with the same Al-(MAO):Zr ratio. The n-MAO approach offers the potential of the MAO being easily chemically modified.