Structural and electronic properties of semiconductor binary microclusters Al n As m − 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 Al n As m − anions in comparison with corresponding neutral cluster. Among different AlAs m − and Al 2 As m − (m=1–7) anions, AlAs 4 − and Al 2 As 3 − are most stable.