HoxH is a subunit of hydrogenase in a unicelluar cyanobacterium Synechocystis sp. PCC6803. We constructed hoxH mutant strain, which the mRNA levels of hoxH reduced to 50% of the wild-type. Total RNAs from three independent wilde-type (GT) and three independent hoxH mutant were labeled by Cy3 followed by hybridyzation on a microarry chip generated by Agilent Technologies (Design ID 036279). Microarray is designed by Prof. Tomohisa Hasunuma, Kobe University.