The influence of the microstructure on the oxidation of poly(1,3-cyclohexadiene) (PCHD) homopolymer, obtained by anionic polymerization with alkyllithium/amine systems, was investigated for the first time. PCHD has a structure consisting of a main chain formed by 1,2-addition (the 1,2-CHD unit) and 1,4-addition (the 1,4-CHD unit). The molar ratio of 1,2-CHD/1,4-CHD units in the polymer chain strongly influenced the extent of oxidation of PCHD. A polymer chain with a high content of 1,4-CHD units was easily oxidized by air and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). In contrast, the progress of oxidation was prevented in the case of PCHD containing 52% of 1,2-CHD units.