Abstract: A process to produce olefins including: (a) Providing a hydrocarbon stream containing at least 10 wt % of pyrolysis plastic oil; (b) Optionally contacting the effluent obtained in step a) with silica gel, clays, alkaline or alkaline earth metal oxide, iron oxide, ion exchange resins, active carbon, active aluminium oxide, molecular sieves, alkaline oxide and/or porous supports containing lamellar double hydroxide modified or not and silica gel, or any mixture thereof; (c) performing a selective hydrogenation step; (d) contacting the stream obtained in step c) with a cracking catalyst to crack the olefins and/or paraffins into olefins having 2 to 4 carbon atoms (e) separating from the effluents obtained at the step d) a first stream containing olefins and saturated hydrocarbons having at most 3 carbon atoms, and a second stream containing hydrocarbons having 4 or more carbon atoms and (f) recovering from said first stream the ethylene and propylene.