Abstract This study is devoted to investigation of spreading of a hypo-eutectic Al 8Si system over a flat Al surface. Wetting kinetics was studied using a real time in situ monitoring of the triple line movement facilitated by a hot-stage microscopy system under controlled atmosphere. Analysis of the validity of the classic Tanner's law correlation developed for inert wetting systems is performed. A good agreement of the power relationship between the triple line location and time was established. The dispersion of the n-power exponent magnitude is between 9 and 13, with an average value of 11.