  An alternating direction implicit (ADI) orthogonal spline collocation (OSC)
method is described for the approximate solution of a class of nonlinear
reaction-diffusion systems. Its efficacy is demonstrated on the solution of
well-known examples of such systems, specifically the Brusselator, Gray-Scott,
Gierer-Meinhardt and Schnakenberg models, and comparisons are made with other
numerical techniques considered in the literature. The new ADI method is based
on an extrapolated Crank-Nicolson OSC method and is algebraically linear. It is
efficient, requiring at each time level only $O({\cal N})$ operations where
${\cal N}$ is the number of unknowns. Moreover,it is shown to produce
approximations which are of optimal global accuracy in various norms, and to
possess superconvergence properties.
