A process suitable for the extraction or recovery of metal values from arsenic containing feeds and including the steps of: a) treating the feed with a nitric acid-containing leachant solution in order to dissolve the desired metals; b) adding a source of iron (III) to the leachant solution whereby to oxidise arsenic (III) in solution to arsenic (V); c) adding a neutralising agent to the leachant solution whereby to precipitate arsenic as arsenic (V); d) separating the arsenic (V) precipitate from the leachant solution; and e) recording metal values from the leachant solution.