The present study describes the swelling/degradation behavior of Ba2+ ions-crosslinked sodium alginate/carboxymethyl guar gum bipolymeric beads which are intended to exhibit greater stability in the environment of changing pH along the gastrointestinal (GI) tract. The beads demonstrated pH dependent swelling as they swelled to nearly 56 +/- 4% in simulating gastric fluid (SGF) of pH 1.2 while 180 +/- 8% water uptake was observed in 6 h in simulating intestinal fluid (SIF) of pH 7.4. followed by degradation. When the beads were put in the media of varying pH (to mimic transition from mouth to colon), the beads remained quite stable for nearly 10 h and then began to disintegrate. It was found that pre-treatment of beads with 0.1 N HCl affected their swellibility. Moreover, on increasing the crosslinking time, the beads demonstrated greater stability but less water uptake. Finally, it was concluded that barium ion-crosslinked bipolymeric beads demonstrate pH-sensitive swelling and are quite stable in the environment of changing pH, thus offering their strong candidature for possible use in oral delivery of drugs along the GI tract. (c) 2005 Elsevier B.V. All rights reserved.