Nanostructured Pt functionalized multiwalled carbon nanotubes (MWNTs) produced by catalytic chemical vapor deposition are good room-temperature hydrogen sensors. MWNTs have been synthesized by catalytic chemical vapor deposition of acetylene using a fixed-bed catalytic reactor over hydrides of Mm(0.2)Tb(0.8)Co(2) obtained through hydrogen decrepitation technique. Purified and chemically treated MWNTs have been functionalized by Pt resulting in nanostructured dispersion of Pt on CNTs. Structural, morphological, and vibrational characterizations have been carried out using XRD, SEM, TEM, HRTEM, Raman spectroscopy, and FTIR spectroscopy, respectively. Dispersion of Pt on MWNTs was confirmed by elemental analysis using EDX. Systematic investigations of hydrogen sensing properties of Pt-MWNT ensembles have been carried out. The Pt-MWNTs thin films are stable after several cycles of adsorption and desorption. The change in electrical resistance due to hydrogen adsorption is reversible, with increases to saturation on exposure to hydrogen gas. The result demonstrates that the Pt-MWNTs are p-type semiconductor materials, and chemically treated MWNTs functionalized with Pt show the better hydrogen sensing response at room temperature.