The invention provides processes for the preparation of both known and novel [bis(substituted-aryl) (indolyl)]methanes and [(substituted-aryl) (heteryl) (indolyl)]methanes, useful as color formers, particularly in carbonless duplicating and thermal marking systems, which comprises the interaction of [bis(substituted-aryl) (phenylsulfonyl)]methanes and [(substituted-aryl) (heteryl) (phenylsulfonyl)]methanes with indoles in the presence of either an alkaline or an acidic catalyst.