There is a clinical need for a synthetic bone graft substitute that can be used at sites of surgical intervention to promote bone regeneration. Poly(vinylphosphonic acid-co-acrylic acid) (PVPA-co-AA) has recently been identified as a potential candidate for use in bone tissue scaffolds. It is hypothesised that PVPA-co-AA can bind to divalent calcium ions on bone mineral surfaces to control matrix mineralisation and promote bone formation. In this study, hydrogels of PVPA-co-AA have been produced and the effect of copolymer composition on the structure and properties of the gels was investigated. It was found that an increase in VPA content led to the production of hydrogels with high porosities and greater swelling capacities. Consequently, improved cell adhesion and proliferation was observed on these hydrogels, as well as superior cell spreading morphologies. Furthermore, whereas poly(acrylic acid) gels were shown to be relatively brittle, an increase in VPA content created more flexible hydrogels that can be more easily moulded into bone defect sites. Therefore, this work demonstrates that the mechanical and cell adhesion properties of PVPA-co-AA hydrogels can be tuned for the specific application by altering the copolymer composition.