In this paper, a new nanostructured Au-TiO2 particle was synthesised and employed for the construction of a label-free amperometric immunosensor for carcinoembryonic antigen (CEA) determination. The spherical Au-TiO2 nanoparticles provided a good microenvironment for the immobilization of biomolecules, enhanced the surface coverage of protein, had large surface-to-volume ratio, film-forming ability and high stability. The Au-TiO2 nanoparticles were characterized by transmission electron microscopy (TEM). The fabrication process of the electrochemical immunosensor was monitored by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. Under optimal conditions, the proposed immunosensor exhibits a good linearity at the studied concentration range from 0.2 to 160.0 ng mL(-1) towards CEA with a coefficient of 0.9965 and a detection limit of 0.06 ng mL(-1) (S/N = 3). Moreover, the proposed immunosensor shows good selectivity, reproducibility, high sensitivity, and would have a potential application in clinical immunoassays. (C) 2010 Elsevier Inc. All rights reserved.