This work uses DFT to investigate diene formation during methanol-to-olefins (MTO) via alkene-mediated and CH₂O-mediated pathways in MFI and CHA zeolites. The rate controlling hydride transfer reactions were investigated with C₁–C₄ surface-bound alkyls present during MTO. In the CH₂O-mediated pathway, rate-determining hydride transfer between surface-bound alkyl and CH₃OH occurs most favorably with tert-butyl where rates of the hydride transfer exceed that of methyl at C₄:C₁ alkyl ratios as low as 10⁻¹⁰ in MFI and 10⁻⁶ in CHA. In the alkene-mediated route, hydride transfers proceed most favorably between C₄H₈ and secondary alkyls to form butadiene, where propyl--C₄H₈ (in MFI) and sec-butyl--C₄H₈ (in CHA) hydride transfers occur over methyl--C₄H₈ when their relative surface concentrations are 10⁻¹⁰ and 10⁻⁵ times that of methyl, respectively. Generally, once formed, C₂₊ surface alkyls are better hydride acceptors than CH₃–Z, suggesting deactivation may be driven by larger surface-bound alkyls, formed by MTO products.