Platinum nanoparticles with a size distribution ranging from 3 to 6 nm were synthesized at room temperature by chemical reduction of platinum chloride, using NaBH4 as the reduction reagent and poly(N-vinylpyrrolidone) as the stabilizer. The Pt colloidal nanoparticles obtained were deposited onto multi-walled carbon nanotubes (MWCNTs) synthesized by the chemical vapor deposition method. Pt/MWCNTs prepared with a metal content of 20 wt% was evaluated as the anode electrocatalyst in a 9 cm2 direct ethanol fuel cell using PtRu/C as the cathode material. Both electrodes had a metal loading of 1 mgPt cm−2. Polarization curves showed higher electroactivity for Pt/MWCNTs than commercial material (Pt/C).