The objective of the present study was to evaluate the physicochemical and biochemical profiling of diphenyl diselenide (PhSe)(2), a selenoorganic compound with biological activity. Experimental protocols were established for chemical stability in isotonic phosphate buffer (PBS) pH 7.4 and in simulated gastric and intestinal fluids, biological stability (bovine serum albumin (BSA) and plasma), solubility in PBS pH 7.4, distribution coefficient (Log D) in octanol/PBS, and determination of free (PhSe)(2) concentrations in BSA and plasma by using liquid chromatography with ultraviolet detection and tandem mass spectrometry. (PhSe)(2) was found to be chemically stable and not susceptible to degradation in plasma. The aqueous solubility was 0.98 +/- 0.072 mu M and the Log D in octanol/PBS system was found to be 3.13. The percentage of unbound fractions of (PhSe)(2) obtained by equilibrium dialysis from BSA and plasma incubated with 100 mu M (PhSe)(2) were 0.69 +/- 0.12 and 0.44 +/- 0.09 %, respectively. The findings indicated that (PhSe)(2) presents chemical and biological stability. Though, the compound showed low aqueous solubility, high Log D value and high binding to plasmatic protein. These data contribute to the knowledge of the toxicokinetic properties of (PhSe)(2) and further explain its low bioavailability in experimental models.