Autocatalysis occurs when one of the products of a reaction acts as a
catalyst for that reaction to occur more rapidly (or at a lower energy if you like). This results in an "
acceleration" of the reaction.
An example of
autocatalysis is the reaction of
permanganate ion with
oxalic acid to form
carbon dioxide and
manganous ion. Once this reaction has occurred the
manganous ion acts as a catalyst to the original reaction. Such reactions are
potentially dangerous, since the
reaction rate may increase to the point of explosion.
The term
autocatalysis is sometimes used outside of the context of
chemistry to describe any
effect which has results that make the original
effect more likely to occur again.