It has been known that an archaebacterium Methanosarcina barkeri strain MS (DSM 800) has a V-type ATPase (Inatomi, K., et al. (1989) J. Biol. Chem. 264, 10954-10959). Here, we report cloning of a cluster of F0F1-ATPase genes from the same organism, the first ever found in archaebacteria. The cluster and encoded subunits exhibit several unusual features such that a gene for delta subunit is lacking, F0-b subunit is unusually large, and gamma subunit is split into two peptide fragments. Attempts to detect F0F1-ATPase proteins and mRNA have been unsuccessful and therefore it is not certain if this gene cluster is really expressed in the cell.