Rapidly solidified Al-5 wt.% Cr alloy has been prepared by the melt spun technique in form of ribbons. Microstructure and subsequent structural changeswere examined as a function of heat treatment usingXRD technique and Rietveld analysis. Metastable Al0.983Cr0.017 and á-Al phases have been observed with 98.1 and 1.9 wt.% contents in the as melt spunribbon, respectively. During heat treatment process at 250 °C for 20h, content of Al0.983Cr0.017metastable phase decreased to 56 wt.% while content of á-Al increased to 39.5 wt.%. In addition, Al45Cr7 phase has beenobserved in the heat treated ribbon with content of 4.5 wt.%. Lattice constant of the as melt spun Al0.983Cr0.017metastable phase has been observed to be less than the equilibrium value referring to that part of Cr has been dissolved in the Al0.983Cr0.017metastable phase. After heat treatment, this value increased to be close to the equilibrium one owing to Cr precipitations. Rapid solidification had a great role for forming theAl0.983Cr0.017metastable phase.