Hydrogenovibrio marinas strain MH-110 is an obligately lithoautotrophic hydrogen-oxidizing bacterium, possessing three sets of the genes for ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO); one form II type (L-x) and two form I type (L8S8) enzymes. The genes for the form I type enzymes are named cbbLS-1 and cbbLS-2, and that for the form II type enzyme is named cbbM. These three sets of genes were cloned in plasmid vectors, and the expression of the genes in E. coli cells were studied. The three RubisCOs were purified through the same steps, and their specificity factors (tau values) were measured. The tau values of CbbLS-1 and CbbLS-2 were higher than that of CbbM, but lower than those of other form I RubisCOs. The specific activity of CbbM was very low and CbbM was inactivated easily during the process of purification. Immunochemical analyses revealed that the antibody against form I type reacted only with CbbL-1 and CbbL-2, and the antibody against form II type reacted only with CbbM. The antibody to neither form of RubisCO demonstrated cross-reactivity for the other form.