Alginate is an attractive material for controlled drug delivery and cell transplantation applications. However, alginate hydrogels are not degradable, have limited mechanical properties, and lack the functional groups required for cell interaction. To address these limitations of alginate while maintaining their favorable characteristics, we have synthesized new polymers derived from sodium poly(guluronate), the portion of the alginate molecule that is responsible for its gelling behaviour. Sodium poly(guluronate) was isolated, oxidized with sodium periodate, and cross-linked with adipic dihydrazide to yield hydrogels with a wide range of mechanical properties, and with cell adhesion peptides coupled to their backbones.