Intervertebral disc (IVD) degeneration is one of the prevailing medical concern and actual health cost. Industries and academic institutions research for therapeutic solutions going from drugs to complete and partial arthroplasty devices as well as engineered tissues. Nucleus pulposus replacement devices (NPRD), and particularly promising hydrogels, are being developed to restore the ``physiological'' state of the intervertebral disc. This project consists in investigating viscoelastic properties of hydrogels immersed in different solutions and at finite deformations. These investigations combined with appropriate mixture theory constitutive modelling should reveal relevant correlations between viscoelastic properties and biochemical information. The aim of the study is to address the major mechanical dissipation sources inherent to the material.