A portable apparatus and method provide on-site permeability measurements of a core sample extracted from a subterranean reservoir. The portable apparatus is easily and conveniently transported to well locations for use on-site, thereby allowing the core sample to be tested in actual reservoir conditions. The apparatus can simultaneously test incoming liquids and liquids passing through the core sample, and can measure data in the forward and reverse flow directions. The apparatus requires only a single pump to pressurize and inject the liquid into the core sample.