Al based alloys (Al-0.1 wt.%Ti, Al-05 wt.%Ti and Al-2 wt.%Li) were prepared using metals of 99.99% high purity in the vacuum atmosphere. These alloys were directionally solidified upward with the different temperature gradients, G, at a constant growth rate, V, and also with the different V at a constant G in the directional solidification apparatus. Cellular spacing, lambda, and microindentation hardness, HV, were measured from both transverse and longitudinal sections of the specimen as a function of solidification processing parameters (G, V and cooling rate, (T) over dot). Dependency of microindentation hardness on the solidification processing parameters and cellular spacing (lambda) in the directionally solidified aluminum alloys were experimentally investigated and the relationships between the solidification processing parameters and microindentation hardness, and cellular spacing and microindentation hardness were obtained by linear regression analysis. The results obtained in this work have been compared with the previous similar experimental results obtained for binary alloys. (C) 2008 Elsevier B.V. All rights reserved.