Since 1983 a large number of small-scale illicit laboratories producing morphine and heroin from commercially available, codeine-based pharmaceutical products have been encountered in New Zealand. The codeine demethylation procedure is based on the use of pyridine hydrochloride. Very simple laboratory equipment and reagents are required and these can be utilised by people with little or no chemical background, following a recipe-like procedure. The process yields a characteristic product known as 'homebake'. This process is fully described.