Time-dependent isochoric formation of methane hydrate was investigated in the presence of low-dose poly(ethylene oxides) (PEOs). The effect of different molecular weights of PEO on methane hydrate nucleation time and storage capacity was studied and compared. Kinetic measurements revealed a dual effect of PEO, including inhibition and stabilization effects, on methane hydrate formation. The nature and type of the effect arises from the difference in molecular weights and concentration ranges of PEOs. These parameters directly affect the nucleation time and storage capacity of methane hydrate. Generally, in comparison with pure water, PEO improved the storage capacity of methane hydrate. PEO (1000kD) at a concentration of 0.5wt% exhibits a significant kinetic inhibitory performance. However, it was an efficient low-dosage hydrate stabilizer at a concentration of 0.25wt%, along with producing gas-rich methane hydrate suitable for gas fuel storage and transportation.