Solvation dynamics of 4-(dicyanomethylene)-2-methyl-6- (p-dimethylaminostyryl) 4H-pyran (DCM) in aqueous solution of a protein, human serum albumin (HSA), is studied using picosecond time-resolved emission spectroscopy. The solvation dynamics of DCM bound to HSA is found to be biexponential with one component of 600 +/- 100 ps (25%) and a very long component of 10 +/- 1 ns (75%). This indicates that the motion of the water molecules in the vicinity of the protein is highly constrained.