The present invention relates to a catalyst composition comprising a modified crystalline aluminosilicate of the Framework Type FER having Si/Al framework molar/ratio greater than 20 characterized in that in said modified crystalline aluminosilicate the ratio between the strong acid sites and the weak acid sites, S/W, is lower than 1.0 and having the extra framework aluminum (EFAL) content lowered to less than 10 wt % preferably 5 wt % even more preferably less than 2 wt % measured by 27Al MAS NMR. The present invention further relates to a process for producing olefins from alcohols in presence of said catalyst composition.