Abstract : This work presents the study of a Surface Plasmon Resonance (SPR) chemical sensor using an optical fibre with an inverted graded index profile. SPR sensing structures based on the use of a bulk dielectric prism or a silica standard optical fibre are currently commercialised. The aim of this study has been to investigate theoretically and experimentally a new kind of optical fibre with an inverted graded index allowing to enhance the performances of this sensor and to simplify its instrumentation. A review of SPR sensors is first presented. Structures based on an optical fibre (single-mode and multimode) are detailed, showing the characteristics of the used devices as well as their performances. A new structure is approached. To make the relatively wide range of core-cladding incident angles as narrow as possible, whatever the incident angles on the input-face of the fibre are, a novel kind of refractive index profile of the core of a multimode fibre has been determined. It has been realised by using a monochromatic point light source suitably positioned on the fibre axis. The ideal profile is an Inverted Graded Index (IGI) profile, close to an inverted parabolic profile. A description of the characteristics of the propagation in such a fibre is given. SPR is then generally described, and its excitation conditions in the IGI fibre are studied. Experimental and theoretical approaches have been investigated to follow the influence of main parameters (nature and thickness of the metallic layer, distance of the source...). The presentation of two practical applications (detection of toluene in water and study in-situ of the growth of a self-assembled monolayer) shows the large fields of applications of the compact and simple optical device developed .