A metal-organic framework (MOP) with a specific construction and pores was demonstrated to have many advanced properties, but still limited to having unique aspects arising from the combination of different MOFs in a single body. Here, we report a facile method to produce MOF-5 crystals with nanocrystalline HKUST-1 (nHKUST-1) embedded into them in what is termed the "nHKUST-1 subset of MOF-5" structure. The results show that the nHKUST-1 subset of MOF-5 structure is capable of Molecular encapsulation by trapping dye molecules in nHKUST-1 particles and embedding them in MOF-5 crystals. Moreover, the gravimetric uptake capacity of nHKUST-1 subset of MOF-5 for methane (CH4) was found to be enhanced as compared to that of MOF-5 or nHKUST-1 alone such that the nHKUST-1 subset of MOF-5 structure exhibits a volumetric capacity of 250% for fuel storage deliverable by the CNG tank at room temperature and 80 bar. Furthermore, it showed robust capacity retention for reversible CH4 uptake cycles at room temperature.