Cytochrome c oxidase (COX) plays important roles in oxidative phosphorylation regulation and oxygen sensing transfer. In the present study, single-nucleotide polymorphisms (SNPs) in three mitochondrially coded subunit genes of COX were identified with the technique of single-strand conformation polymorphism in Tibet Chicken and four lowland chicken breeds-Dongxiang Chicken, Silky Chicken, Hubbard ISA White broiler, and Leghorn layer. In total, 14 SNPs were identified in the three genes of COX of the five chicken breeds, and 13 haplotypes were defined for the 14 SNPs. This work will afford reference for the further study on the association of COX with the adaptation to hypoxia.