Using the reductive perturbation technique, the propagation characteri
stics of ion-acoustic double layer in a spatially inhomogeneous plasma
have been investigated. We have derived a modified Korteweg-de Vries
(mKdV) equation with varying coefficients for an inhomogeneous plasma
with two Maxwellian electron species. The double layer solution of the
mKdV equation is discussed in detail. The present analysis shows that
the inhomogeneous plasma density n0 does not affect the amplitude of
the double layer, phi(m), whereas its width and velocity are found to
decrease as it propagates in the higher density region. It is found th
at the peak compressed (rarefied) ion density, n(1m), corresponding to
compressive (rarefactive) double layer increases as the double layer
moves along the positive density gradient. The relevance of the presen
t theory to the space plasmas is pointed out.