We generalize the continuous time random walk (CTRW) to include the effect
of space dependent jump probabilities. When the mean waiting time diverges
we derive a fractional Fokker-Planck equation (FFPE). This equation describ
es anomalous diffusion in an external force field and close to thermal equi
librium. We discuss the domain of validity of the fractional kinetic equati
on. For the force free case we compare between the CTRW solution and that o
f the FFPE.