A process for hydrogenating unsaturations in petrochemical feedstocks, the process comprising contacting the petrochemical feedstock, including at least one component having unsaturations, and hydrogen with a catalyst comprising at least one Group Ia, Ib, IIb, VIb, VIIb or VIII metal on a support of a crystalline calcium silicate having a surface area of at least 30 m2/g, the support being in the form of substantially spherical particles having a mean diameter of from 10 to 200 microns and pores in the particles having a diameter of from 100 to 2000 Angstroms, at a temperature of from 0 to 550.degree. C. and a pressure of from 3 to 150 barg.