Abstract: This invention relates to a catalyst composition for polymerization of propylene, having high activity and producing polypropylene of high stereoregularity and having a low particle size distribution, which comprises;1. reducing TiCl.sub.4 by diethylaluminum chloride (DEAC), thereby forming a reduced solid (TiCl.sub.3),2. removing the aluminum compounds from the reduced catalyst,3. treating the said reduced solid with the mixture or complex of TiCl.sub.4 and diisoamylether (IAE) and4. separating the solid catalyst from the mixture.The aluminum compounds may be removed by washing with a complexing agent therefor; in a preferred embodiment the complexing agent is di-n-butyl ether.