The self-assembly of catalytic nanoparticles by the decomposition of an as-deposited oxidized CoCrPt thin film is investigated, and the feasibility of its use in fabricating vertically aligned SWCNT films at a low synthesis temperature (∼600 °C) by microwave plasma CVD is described. The XPS results indicate that small nanoparticles with the diameters of 3–3.5 nm were formed in the explosion associated with the reduction of PtO 2 in the CoCrPtO x film. Cr 2O 3 is employed to inhibit the agglomeration of nanoparticles and Co is typically involved in the dissolution and precipitation of carbon species for SWCNT growth. These small, self-assembled catalytic nanoparticles obtained from the CoCrPtO x ultra-thin film can be used to fabricate an extremely dense and highly oriented SWCNT film on a silicon wafer at a temperature of ∼600 °C.