Mitochondria capable of oxidative phosphorylation and respiratory control have been isolated from Solatium tuberosum L. using polyvinylpyrrolidone as a complexing agent for oxidizing compounds formed during cellular disruption. An intermittent low speed centrifugation at 200 xg combined with isolation medium containing mannitol, bovine serum albumin and cysteine proved satisfactory for the sendimentation of starch and separation of functional mitochondria having high protein content.