In this work, poly(methyl methacrylate)/ammonia borane/multiwall carbon nanotube (PMMA/AB/MWCNT) nanofiber composites have been fabricated and the synergetic nanoconfinement effect of nanofiber and CNT components on dehydrogenation temperature and liberating unwanted byproducts of AB (NH3BH3) have been studied. The results of dehydrogenation of PMMA/AB and PMMA/AB/MWCNT samples show 112 and 85 A degrees C exothermic reaction temperatures, which are dramatically lower than pure AB (120 A degrees C). Furthermore, by capture and interaction of AB molecules in the MWCNT and PMMA nanofiber structures, the enthalpy of exothermic decomposition decreases from -21.00 to -1.83 kJ mol(-1) H-2, suggesting that this type of AB nanofiber composite can provide a convenient reversible hydrogen storage material. The utilization of MWCNT as carbon catalyst and confining of AB result in a decrease of ammonia borane weight loss from 60.00 to 2.88 wt% which in turn can vigorously decline the emission of byproduct impurities. The synthesis process of PMMA/AB/MWCNT nanofiber composites causes the crystal structure of AB particles changed to the amorphous structure which has been clearly confirmed by X-ray diffraction analyses. The strategy of combining nanofiber structure and MWCNT as carbon catalyst with AB particles can be presented as a practicable solution to reach lower operational temperature and to decline undesirable volatile products.