The present invention relates to protein-coated micro-crystals and their method of preparation. The protein-coated micro-crystals may find particular application in preparing enzymes for use as biocatalysts; preparation of therapeutic proteins for use in pharmaceutical formulations; production of cleansing agents comprising enzymes; production of paints, varnishes, coatings, films and the like comprising proteins which impart protective and/or antifouling properties; production of films, polymers, inks, coatings, electrodes and/or optical materials comprising proteins for diagnostic kits and/or biosensor applications; use of proteins for studies of molecular recognition, molecular binding and inhibitor binding in non-aqueous media; and preparation of protein based food additives.