Al doped ZnO (AZO) thin films for different compositions were deposited by using solgel technique. Thin film preparation, structural, optical and electrical properties have been studied. Investigations on the effect of structural, optical and electrical properties revealed the relationship that exists between these properties and the film lattice defect distribution. XRD studies showed that AZO thin films a preferred orientation (002) direction, and decrease in the lattice distance indicating a less defected structure. The electrical and optical properties of AZO films have reached a good level. Films with electrical resistivity as low as 1.84 × 10−3 Ω cm and 90 % optical transmittance in the visible region, which is suitable for gas sensing applications. It is found that electrical resistivity was due to increase in concentration of donor atoms. (Received July 8, 2017; Accepted December 20, 2017) © 2017, Virtual Institute of Physics of the Foundation Horia Hulubei. All rights reserved.