A process and an apparatus for flow extraction whereby a substance dissolved in a first solvent is extracted over to a second solvent which is insoluble in the first. The two solvents are brought together via two legs in a T-tube, and the mixture exits through the third leg, the cross-sectional areas of the legs being dimensioned to produce segmented flow with alternating plugs of the second and first solvents. The ratio between the cross-sectional areas of the tube legs for the first and second solvents is 2-8:1, preferably 4:1. Between the first and third legs carrying the confluent flows, the ratio between the cross-sectional areas thereof is reduced to 0.7-1.2:1, preferably 1:1, at a distance from the juncture which is 1-3 times the inner diameter of the third leg. The confluent flow is led through a spiral hose, producing a powerful extraction due to the counter-current turbulence.