Previous work on vortex ring-induced extraction in a batch cell has formed the basis for design of a continuous multistage extractor. The unit consists of a 3.0 m long rectangular tank divided into five compartments by four pneumatically driven reciprocating plate modules. The reciprocating plates generate a series of vortex rings which pump the liquid phases countercurrently and provide interfacial contact. Baffles in each module prevent backflow between the compartments. Stage efficiencies have been measured for the extraction of benzoic acid from kerosene to water.