Process for producing a feed stream for a steam reforming plant containing at least one reforming stage, comprising the following steps: (a) provision of a first liquid input stream containing olefins and a second input stream comprising hydrogen, (b) combining of the first input stream and the second input stream to form a hydrogenation input stream, (c) heating of the hydrogenation input stream in a heating apparatus and vaporization of the hydrogenation input stream in a vaporization apparatus, (d) introduction of the heated and vaporized hydrogenation input stream into a hydrogenation reactor comprising at least one hydrogenation zone, at least partial conversion of the olefins present in the hydrogenation input stream in the hydrogenation reactor under olefin hydrogenation conditions, discharge of a gaseous olefin hydrogenation product stream from the hydrogenation reactor, (e) separation of the olefin hydrogenation product stream in a separation apparatus into a gaseous reforming feed stream which is fed into a steam reforming plant and a gaseous recycle stream, (f) cooling of the gaseous recycle stream, with this being at least partially condensed and subsequently introduced into a phase separation apparatus in which it is separated into a gaseous partial recycle stream and a liquid partial recycle stream, (g) discharge of the gaseous partial recycle stream and the liquid partial recycle stream from the phase separation apparatus, with the gaseous partial recycle stream being combined with the second input stream and the liquid partial recycle stream being combined with the first input stream and/or being recirculated to process step (b). (a) provision of a first liquid input stream containing olefins and a second input stream comprising hydrogen, (b) combining of the first input stream and the second input stream to form a hydrogenation input stream, (c) heating of the hydrogenation input stream in a heating apparatus and vaporization of the hydrogenation input stream in a vaporization apparatus, (d) introduction of the heated and vaporized hydrogenation input stream into a hydrogenation reactor comprising at least one hydrogenation zone, at least partial conversion of the olefins present in the hydrogenation input stream in the hydrogenation reactor under olefin hydrogenation conditions, discharge of a gaseous olefin hydrogenation product stream from the hydrogenation reactor, (e) separation of the olefin hydrogenation product stream in a separation apparatus into a gaseous reforming feed stream which is fed into a steam reforming plant and a gaseous recycle stream, (f) cooling of the gaseous recycle stream, with this being at least partially condensed and subsequently introduced into a phase separation apparatus in which it is separated into a gaseous partial recycle stream and a liquid partial recycle stream, (g) discharge of the gaseous partial recycle stream and the liquid partial recycle stream from the phase separation apparatus, with the gaseous partial recycle stream being combined with the second input stream and the liquid partial recycle stream being combined with the first input stream and/or being recirculated to process step (b).