Abstract: A typical kinase family, ABC1 (the activity of bc1 complex) genes play essential roles in plant growth, development and responses to be environmental stresses. We cloned and characterized a gene of the ABC1 family in Arabidopsis. Semi-quantitative RT-PCR and GUS staining analysis revealed that it was constitutively expressed and mainly induced under methyl viologen (MV) treatment. AtOSAK1-GFP fusion analysis showed that AtOSAK1 is localized in chloroplasts. Transgenic plants overexpressing AtOSAK1 showed higher rates of seed germination and seedling survival to MV stress than that of the Col-0 and the knock-out mutant osak1. These results suggested that AtOSAK1 may be involved in response to oxidative stress in Arabidopsis.