The variations of the electrical conductivity with temperature and electric field of the ternary alloy of gallium, aluminium and arsenic (Al0.75Ga0.25As) with atomic compositions of 99/1 and 98/2 have been investigated. The electrical conductivity of the alloy increases with temperature according to the relation, ? = ?0 exp (??/kT). The activation energy calculated from this empirical relation is 1.42±0.01 eV. The investigation of the variation of electrical conductivity with electric field of the samples reveals that in the low field region (< 1,400 V/m), the conduction is ohmic while in the high field region (> 1,400 V/m), the results are interpreted in terms of space charge limited currents.