An improved OXO process with converted waste oil recycle includes: (a) hydroformylating an olefin with synthesis gas in a reactor to produce an 0X0 product as well as by-product waste oil, the by-product waste oil having a lower or higher boiling temperature than said 0X0 product; (b) separating 0X0 product from the by-product waste oil; (c) converting separated waste oil to synthesis gas; and (d) recycling the synthesis gas produced in step (c) to the reactor of step (a).