A process for the conversion of a liquid hydrocarbon feedstock into lower molecular weight hydrocarbon compounds in an ebullated-bed catalytic hydroprocessing reactor, wherein the ebullated-bed reactor includes an internal recycle downflow conduit in fluid communication with the substantially catalyst-free region above the catalyst bed for receiving hydrocarbons heavier than recovered products; the process comprising: mixing the liquid hydrocarbon feedstock with an excess of hydrogen gas in a mixing zone to dissolve a portion of the hydrogen gas in the liquid hydrocarbon feedstock to produce a hydrogen-enriched liquid hydrocarbon feedstock; conveying the hydrogen-enriched liquid hydrocarbon feedstock and undissolved hydrogen to a flashing zone in which at least a portion of undissolved hydrogen gas is flashed; passing the hydrogen-enriched liquid hydrocarbon feedstock from the flashing zone to the feed inlet of the ebullated-bed reactor for reaction that includes conversion of the feedstock into lower molecular weight hydrocarbons; recovering converted hydrocarbon products of lower molecular weight from a substantially catalyst-free region of the ebullated-bed reactor; passing the hydrocarbons from the internal recycle downflow conduit at the bottom of the ebullated-bed reactor to an external recycle separation zone which includes an external separation or flash vessel in fluid communication with the internal recycle downflow conduit and an outlet in fluid communication with a recycle ebullating pump for passing the separation or flash vessel bottoms to the inlet of the ebullated-bed reactor; wherein a portion of a tops stream containing light gases and hydrogen is recovered from the external recycle separation zone and recycled to the external separation or flash vessel passing the external separation or flash vessel bottoms from which hydrogen and light gases have been removed to the recycle ebullating pump; and passing the separation or flash vessel bottoms from the recycle ebullating pump to the inlet of the ebullated-bed reactor. mixing the liquid hydrocarbon feedstock with an excess of hydrogen gas in a mixing zone to dissolve a portion of the hydrogen gas in the liquid hydrocarbon feedstock to produce a hydrogen-enriched liquid hydrocarbon feedstock; conveying the hydrogen-enriched liquid hydrocarbon feedstock and undissolved hydrogen to a flashing zone in which at least a portion of undissolved hydrogen gas is flashed; passing the hydrogen-enriched liquid hydrocarbon feedstock from the flashing zone to the feed inlet of the ebullated-bed reactor for reaction that includes conversion of the feedstock into lower molecular weight hydrocarbons; recovering converted hydrocarbon products of lower molecular weight from a substantially catalyst-free region of the ebullated-bed reactor; passing the hydrocarbons from the internal recycle downflow conduit at the bottom of the ebullated-bed reactor to an external recycle separation zone which includes an external separation or flash vessel in fluid communication with the internal recycle downflow conduit and an outlet in fluid communication with a recycle ebullating pump for passing the separation or flash vessel bottoms to the inlet of the ebullated-bed reactor; wherein a portion of a tops stream containing light gases and hydrogen is recovered from the external recycle separation zone and recycled to the external separation or flash vessel passing the external separation or flash vessel bottoms from which hydrogen and light gases have been removed to the recycle ebullating pump; and passing the separation or flash vessel bottoms from the recycle ebullating pump to the inlet of the ebullated-bed reactor.