The AlCl3-catalysed chlorination and deuteration reactions of 7-Me3N-nido-7-CB10H12 are presented. When 7-Me3N-nido-7-CB10H12 is treated with anhydrous HCl in the presence of AlCl3 electrophile induced nucleophilic chlorination occurs to yield 7-Me3N-9-Cl-nido-7-CB10H11 as the major product with a minor component of the disubstituted species, 7-Me3N-6,9-Cl-2-nido-7-CB10H10. When DCl in the presence of AlCl3 is used deuterium substitution occurs in addition to chlorination and with the formation of 7-Me3N-9-C-1-1,4,5,6,10-D-5-nido-7-CB10H10. A similar dichlorinated by-product 7-Me3N-6,9-Cl-2-1,4,5,10-D-4-nido-7-CB10H6 is also obtained. The structures of all isolated compounds were unambiguously determined via elemental analyses, IR mass spectroscopy, H-1, B-11 and 2-D B-11- B-11 NMR spectra.