The results of DFT investigation suggest that C2–C3 bond cleavage of the 2,2-dianisyl-3,3-dimethyl-4-methylenecyclobutanone radical cation (2b + ) is preferred from both a thermodynamic and a kinetic perspective while C1–C2 bond cleavage is both thermodynamically and kinetically favored in the parent methylenecyclobutanone radical cation (MCB + ) and the 2,2-diphenyl- and 2,2-dianisyl-4-isopropylidenecyclobutanone radical cations (1a-b + ). The DFT calculations also suggest that a bonding character exists in C2–C3 bond of the 2,2-diphenyl-3,3-dimethyl-4-methylenecyclobutanone radical cation (2a + ) but not in that of 2b + . Consequently, the unique reactivity of 2b + can be accounted for by the existence of the steric hindrance between methyl and anisyl substituents, which favors C2–C3 bond cleavage, and the absence of C2–C3 bonding character. Those results support that the previous experimental results of photoinduced electron-transfer reactions of 1 and 2. The combined factors comprise stereoelectronic substituent effects that lead to a drastic change in the reaction pathways followed by 2b + relative to that of other methylenecyclobutanone-type radical cations.