A gene encoding a Na$^+$/H$^+$ antiporter was obtained from the genome of Halobacillus aidingensis AD-6$^T$, which was sequenced and designated as nhaH. The deduced amino acid sequence of the gene was 91 % identical to the NhaH of H. dabanensis, and shared 54 % identity with the NhaG of Bacillus subtilis. The cloned gene enable the Escherichia coli KNabc cell, which lack all of the major Na$^+$/H$^+$ antiporters, to grow in medium containing 0.2 M NaCl or 10 mM LiCl. The nhaH gene was predicted to encode a 43.5 kDa protein (403 amino acid residues) with 11 putative transmembrane regions. Everted membrane vesicles prepared from E. coli KNabc cells carrying NhaH exhibited Na$^+$/H$^+$ as well as Li$^+$/H$^+$ antiporter activity, which was pH-dependent with the highest activity at pH 8.0, and no K$^+$/H$^+$ antiporter activity was detected. The deletion of hydrophilic C-terminal amino acid residues showed that the short C-terminal tail was vital for Na$^+$/H$^+$ antiporter activity.