C-reactive protein (CRP) is a protein present in plasma and is one of the most expressed proteins in acute phase inflammationcases, being a known biomarker of inflammatory states. Detection and quantification of CRP in an easy, cheap, and fast waycan improve clinical diagnostics in order to prevent serious inflammatory states.In this work, we study the electrochemical and optical properties of protein G layer grafted on gold microelectrodes withimpedance spectroscopy and surface plasmon resonance imaging techniques for C-reactive protein detection. Two CRPantibodyimmobilization methods were used: the first method is based on direct physisorption of CRP-Antibody onto goldmicroelectrodes; the second one is based on oriented CRP-antibody with protein G intermediate layer. The two developedimmunosensors were tested in presence of CRP antigen in phosphate buffer saline solution with impedance spectroscopy andsurface plasmon resonance imaging The reproducibility was tested against five substrates prepared in the same conditions atroom temperature. The negative control was obtained after different injection of antigen-rabbit onto gold microelectrode coatedonly with anti-CRP antibody.