Structural and electronic properties of semiconductor binary microclusters AlnAsm- anions have been investigated using the B3LYP-DFT method in the ranges of n=1,2 and m=1-7. Full structural optimization, adiabatic electron affinities calculation and frequency analysis are performed with the basis of 6-311+G(d). The charged-induced structural changes in these anions have been discussed. The strong As-As bond is also favored over Al-As bonds in the AlnAsm- anions in comparison with corresponding neutral cluster. Among different AlMm- and Al2Asm-(m=1-7) anions, AlAs4- and Al2As3- are most stable. (c) 2005 Elsevier B.V. All rights reserved.