Optimization of extraction conditions of the proanthocyanidins (PAC) and PAC-rich extract (PACE) from bark of alder species (Alnus incana and Alnus glutinosa) were performed varying solvents (ethanol, distilled water), extraction methods (conventional and microwave assisted extraction), extraction temperature (20–120 °C) and extraction times (5–60 minutes). The optimal extraction conditions established in the work provide 87 % PAC transition from the bark of alder species to hydrophilic extracts. On the basis of the extraction results, the technological scheme of PAC and PACE isolation from grey alder bark with focus on biorefinery was developed.