The morphological characteristics of multi-walled carbon nanotubes with multi-vacancy defects were reported, showing the potential of such nanotubes as supports for decorating Pt nanoparticles. Multi-carbon vacancies on multi-walled carbon nanotubes were introduced by oxidizing cobalt oxide-decorated multi-walled carbon nanotubes at 250C for 6h in air by means of a carbon gasification reaction. This resulted in holes and thinned walls on multi-walled carbon nanotubes. It was revealed that creating multivacancy defects led to an increase in the specific surface area from 107 to 152m2/g and a pore size increase from 5 to 8nm on multi-walled carbon nanotubes as compared with that of pristine multi-walled carbon nanotubes. Some 30wt% of Pt was decorated onto the multi-walled carbon nanotubes by impregnation in order to investigate the effect of carbon vacancies upon the degree of Pt dispersion, and the presence of Pt metal was confirmed by X-ray diffraction. Transmission electron microscopic images clearly showed that Pt nanoparticles with an average particle size of 2.8nm were evenly dispersed on the defective site of holes and thinned walls. This was clear evidence that the defective sites of multi-walled carbon nanotube were active and were good anchor sites for metal decoration.Multi-Walled Carbon Nanotube with Multivacancy Defects: Porous Structure and Pt Decoration. D.H.Kim: Journal of Nanoscience and Nanotechnology, 2014, 14[6], 4557-63