The aim of this thesis was to expand the sensing capabilities of a conducting polymer-based sensor platform developed in our laboratory. The platform itself is composed of a polyaniline - poly(vinylsulphonate) (PANIIPVS) modified screen-printed carbon paste electrode used as a substrate for the immobilisation of antibody, and the subsequent competition assays of protein analytes. Chapter 1 is a literature review encompassing the field of electrochemical immunosensing. chapter 3 outlines work towards developing real-time imrnunosensors to oestradiol and p60. This ork involved the synthesis of horseradish peroxidase (HRP) conjugates with oestradiol, and p60 or use in a competitive immunosensor, as well as immunoassay characterisation of the proteins, nd their application to the biosensor platform. Chapter 4 outlines efforts to address sub-monolayer protein immobilisation issues to the PANIIPVS matrix by optimising experimental parameters overning the electrostatic irnmobilisation process. It also details experiments probing icroperoxidase-11 as an alternative labeling enzyme to HRP. Chapter 5 deals with the investigation of a novel surfactant-based strategy to reduce non-specific interactions between species present in the bulk solution, and the PANIIPVS matrix. This research highlights the need for developing the technology for real-time electrochemical immunosensing, and examines some of the critical issues involved.