In a process for the production of pumpable coal slurries for use in high-pressure hydrogenation, such an amount of finely divided coal is mixed into an oil which boils at a temperature of higher than about 200.degree. C., as not to exceed the limit of pumpability in respect of the slurry produced. The slurry is treated for about 0.5 to 15 minutes at a temperature of from 280.degree. to 450.degree. C., possibly under elevated pressure. Such a further amount of finely divided coal is mixed into the slurry after the above-indicated treatment, that the limit of pumpability is once again not exceeded. After the addition of the further amount of finely divided coal, the slurry can optionally be subjected again to heat treatment. This mode of operation permits the production of slurries with an elevated coal content, without coking occurring or pumpability being lost when the slurries are heated to hydrogenation temperature.