A reaction system for preparation of a viscoelastic polyurethane foam comprising: (a) an organic polyisocyanate; and (b) an isocyanate reactive component comprising: (i) from 10 to 50% by weight of the isocyanate reactive component of one or more low equivalent weight propylene oxide rich (PO-rich) polyols having a combined number average equivalent weight from 200 to 500 and a propylene oxide content of at least 70% by weight of the total mass of the PO-rich polyol; (ii) from 45 to 80% by weight of the isocyanate reactive component of one or more ethylene oxide (EO-rich) polyols having a combined number average equivalent weight from 200 to 800 and an ethylene oxide content from 30% to 75% by weight of the total mass of the EO-rich polyol; and at least one of (iii) from 10 to 30% by weight of the isocyanate reactive component of one or more high equivalent weight propylene oxide rich (PO-rich) polyols having a number average equivalent weight from 800 to 2,000 and a propylene oxide content of at least 70% by weight of the total mass of the PO-rich polyol; and (iv) from 10 to 40% by weight of the isocyanate reactive component of one or more propylene oxide co-polymer polyols containing styrene-acrylonitrile. (a) an organic polyisocyanate; and (b) an isocyanate reactive component comprising: (i) from 10 to 50% by weight of the isocyanate reactive component of one or more low equivalent weight propylene oxide rich (PO-rich) polyols having a combined number average equivalent weight from 200 to 500 and a propylene oxide content of at least 70% by weight of the total mass of the PO-rich polyol; (ii) from 45 to 80% by weight of the isocyanate reactive component of one or more ethylene oxide (EO-rich) polyols having a combined number average equivalent weight from 200 to 800 and an ethylene oxide content from 30% to 75% by weight of the total mass of the EO-rich polyol; and at least one of (iii) from 10 to 30% by weight of the isocyanate reactive component of one or more high equivalent weight propylene oxide rich (PO-rich) polyols having a number average equivalent weight from 800 to 2,000 and a propylene oxide content of at least 70% by weight of the total mass of the PO-rich polyol; and (iv) from 10 to 40% by weight of the isocyanate reactive component of one or more propylene oxide co-polymer polyols containing styrene-acrylonitrile. (i) from 10 to 50% by weight of the isocyanate reactive component of one or more low equivalent weight propylene oxide rich (PO-rich) polyols having a combined number average equivalent weight from 200 to 500 and a propylene oxide content of at least 70% by weight of the total mass of the PO-rich polyol; (ii) from 45 to 80% by weight of the isocyanate reactive component of one or more ethylene oxide (EO-rich) polyols having a combined number average equivalent weight from 200 to 800 and an ethylene oxide content from 30% to 75% by weight of the total mass of the EO-rich polyol; and at least one of (iii) from 10 to 30% by weight of the isocyanate reactive component of one or more high equivalent weight propylene oxide rich (PO-rich) polyols having a number average equivalent weight from 800 to 2,000 and a propylene oxide content of at least 70% by weight of the total mass of the PO-rich polyol; and (iv) from 10 to 40% by weight of the isocyanate reactive component of one or more propylene oxide co-polymer polyols containing styrene-acrylonitrile.