The impregnation of H3PW12O40 (referred as HPW) heteropolyacid on the Al-MCM-41 solid noticeably enhances by 2-3 times the Brönsted acidity with respect to the bare host. Catalytic evaluation confirms that 1wt %Pt/25wt.%HPW/Al-MCM-41 catalyst is active for n-heptane isomerization in the presence of hydrogen under atmospheric condition. The n-heptane conversion linearly increases with increasing the reaction temperature, while, the selectivity to isoheptanes gradually decreases. 2-methylhexane is predominant in the monobranched isomers and 2, 3 dimethylpentane is the prevailing compound more than 50 % in the multibranched isomer products. The molar ratio of multibranched to monobranched isoheptanes varies within a narrow range between 0.8 and 1.2, and this ratio is much higher than that reported in the literature at similar reaction conditions using zeolites containing catalysts.