  The di-photon decay channel of the lightest Higgs boson is considerd as a
probe to explore CP violation in the Minimal Supersymmetric Standard Model
(MSSM). The scalar/pseudo-scalar mixing is considered along with CP violation
entering through the Higgs-sfermion-sfermion couplings, with and without light
sparticles. The impact of a light stop on the decay width and Branching Ratio
(BR) is established through a detailed study of the amplitude of the process H1
--> gamma.gamma. The other sparticles have little influence even when they are
light. With a suitable combination of other MSSM parameters, a light stop can
change the BR by more than 50 % with a CP-violating phase phi_mu ~ 90 deg.,
while the change is almost nil with a heavy stop.
