Nanocomposites of poly(vinyl alcohol) (PVA) with iron, cobalt, or nickel sulfides were successfully prepared using a hydrothermal process by an in situ reaction with CS2 at 140 degreesC for 8 h. XRD results showed that pure phases of FeS2, CoS2, and NiS were obtained in the as-prepared nanocomposites. They also showed that the crystallinity of PVA was largely decreased after incorporation of the nano-sized sulfides. This was also confirmed by IR spectroscopy. SEM photographs showed that the sulfide particles were homogeneously dispersed in the PVA matrix. UV-visible spectroscopy was also used to characterize the as-prepared nanocomposites,