In this work, we present the results of a rare class of nonpolymeric molecules that show significant performance as stand-alone kinetic gas hydrate inhibitors (KHIs). n-Butylated amine oxides of four nonpolymeric oligoethyleneamines, pentaethylenehexamine (PEHA), tetraethylenepentamine (TEPA), triethylene tetramine (TETA), diethylenetriamine (DETA) (all made from ammonia and ethylene) with molecular weights in the range 103-232 D, as well as four hyperbranched polyethylenimines (HPEIs) (made from aziridine), with molecular weights in the range of 0.3-10.0 kDa, have been synthesized and evaluated for their KHI performance. All the amine oxides were first evaluated by carrying out slow constant cooling experiments (1 degrees C/h) at 76 bar with a Structure II hydrate-forming gas in steel rocking cells. The butylated hyperbranched polyethylenimine oxides (HPEI-Bu-AOs) showed molecular weight KHI performance dependence. The performance increased with decreasing molecular weight of the polymer with HPEI-Bu-AOs prepared from low-molecular-weight oligoethylenimines (MWs 0.3 kDa and 0.6 kDa) showing the best KHI performances, with average onset temperatures (T-o) from 10 parallel experiments of 6.4 and 6.7 degrees C, respectively. Among the oligoethyleneamine oxides, TEPA-Bu-AO, based on TEPA (MW approximate to 190 Da) showed a KHI performance, T-o = 6.7 degrees C, similar to that of the best HPEI-Bu-AOs. The best amine oxides from the screening tests were further investigated in long-term isothermal experiments at 4.1 degrees C and similar to 30 bar, giving a subcooling (Delta T) of 7.5 degrees C. Using 5000 ppm additive, HPEI-Bu-AO-0.3kD and HPEI-Bu-AO-0.6kD were superior KHIs to the best performing nonpolymeric oligoethyleneamine oxide, TEPA-Bu-AO. The HPEI-Bu-AO-0.3kD compound and its 0.6kD analogue showed hold times of 10-13.6 days, while TEPA-Bu-AO showed a hold time of 6.5 days under the same test conditions. All these three oligomeric amine oxides exhibited no cloud point up to 100 degrees C as 1.0 wt % solutions in deionized water.