Abstract: Tobacco (donor tobacco) is contacted with a receiving substrate which has been treated with a strong acid or an ammonium salt of a strong acid. Part of the nicotine in the donor tobacco is transferred from the donor tobacco to the receiving substrate. Thereafter the donor tobacco and the substrate may be separated. The donor tobacco has a reduced nicotine content and hence more desirable for use in a smoking product. Where the receiving substrate is a low nicotine tobacco by-product (or artificial smoking material) said substrate, enriched in nicotine as a result of the transfer, may be used as a filler material for smoking products.