The results of tetraethylenepentamine polyalkylated amine oxides (TEPA-R-AO) and hyperbranched polyethyleneimine polyalkylated amine oxides (HPEI-R-AO) as kinetic inhibitors for methane hydrate are reported. Alkyl groups with 2 to 6 carbon atoms and different end-branchings (n-, iso- and tert-) were investigated. In slow constant cooling experiments, the best HPEI-R-AO derivatives outperformed the best TEPA-R-AO derivatives. The amine oxides with pentyl and hexyl groups gave better KHI performance than the butylated species. The best HPEI-R-AO with pentyl and hexyl groups gave such good results they were investigated further in long-term isothermal method at a subcooling degree of 11.3 °C. The HPEI-R-AO with 6 carbon atom alkyl groups gave the longest induction times. 2-butoxyethanol gave good synergy on the polymers with branched alkyl groups. The amine oxide functional group is a key feature because substitution with zwitterionic or cationic groups significantly decreased the performance whilst keeping the size of the alkylation groups constant.