Abstract <p>This study compares the kinetics of key non-catalytic processes—thermal pyrolysis, partial oxidation, steam reforming, and dry reforming—for methane and C₂₊ hydrocarbon conversion at 1400–1800 K, highlighting both common and distinct behavioral trends. The first oxidative conversion step differs markedly between methane and its heavier homologues. Methane conversion is primarily driven by its reaction with oxygen, with both reactants being consumed synchronously. In contrast, even in the presence of oxygen, C₂₊ hydrocarbons initially undergo thermal pyrolysis—a more rapid process under these conditions—before participating in slower oxidative reactions with O₂, H₂O, or CO₂. The main oxidation reactant is ethylene, a compound produced through thermal pyrolysis of C₂₊ hydrocarbons: it reacts with O₂ to form CO and H₂O. All C₂₊ hydrocarbons show comparable O₂ conversion rates during non-catalytic partial oxidation—significantly higher than those observed for methane. Once oxygen has been fully consumed, further hydrocarbon conversion proceeds with slower reactions, primarily involving CO, C₂H₂, and CH₄. In this reaction zone, H₂O serves as the primary conversion agent, along with CO₂ when present. These reactions substantially boost the H₂ content in the syngas.</p>