The notion of q-Brownian motion introduced by Majid is extended to bra
ided spaces corresponding to a generic R-matrix, and combined with the
theory of quantum probability. This leads to a definition of diffusio
ns on these spaces, The corresponding heat equations (difference-diffe
rential equations) are solved in terms of Appell polynomials (i.e., sh
ifted moment systems). Some examples of interest for applications are
given. (C) 1998 American Institute of Physics.