A nido-closo-nido interconversion reaction of 7-Me3N-nido-7-CB10H12 is discussed. Nido-[8-HO-7-CB10H12]- anion is obtained from the reaction of 7-Me3H-nido-7-CB10H12 with sodium hydride. At ambient temperature the initial product is the deprotonated species, nido-[7-Me3N-7-CH10H11]-, but after reflux and hydrolysis the isolated product is the nido-[8-HO-7-CH10H12]- anion with the closo-[2-CB10H11]- as an intermediate. The results unambiguously show [OH] substitution at B (8) position.