Sn-1.2 wt.% Cu alloy was prepared in a graphite crucible under the vacuum atmosphere. The samples were directionally solidified upwards under argon atmosphere with different temperature gradients (G = 2.69-8.88 K/mm) at a constant growth rate (V = 6.80 mu m/s) and with different growth rates (V = 2.78-136.36 mu m/s) at a constant temperature gradient (G = 2.69 K/mm) by using a Bridgman-type directional solidification apparatus. The microstructure of Sn-1.2 wt.% Cu alloy seems to be rod eutectic structure. The rod spacings (lambda) were measured from both transverse and longitudinal sections of the samples. The influence of the growth rate (V) and temperature gradient (G) on the rod spacings (lambda) and undercoolings (Delta T) was analysed. The values of lambda(2)V, lambda(2)G, Delta T lambda, Delta TV(-0.5) and Delta TG(0.5) were determined by using the Jackson-Hunt eutectic theory. The results obtained in the present work have been compared with the similar experimental results obtained in the previous works for binary alloys. (C) 2009 Elsevier B.V. All rights reserved.