An amperometric glucose biosensor was developed using an anionic clay matrix (layered double hydroxide (LDH), Ni/Al-NO3) for the immobilization of glucose oxidase (GOx). The biofilm was prepared by electrodeposition of the clay and GOx and subsequent cross-linking with glutaraldeyde. The Pt surface modified with the Ni/Al-NO3 shows a much reduced noise, giving rise to a better signal to noise ratio for the currents relative to H2O2 oxidation, and a linear range for H2O2 determination wider than the one observed for bare Pt electrodes. Under the optimised operative conditions, the performances of the biosensor have been evaluated by measuring the steady-state currents (at +0.45 V versus SCE) to increasing concentrations of glucose in "air saturated" 0.1 M phosphate buffer (pH 7.0). Both batch and flow injection modes were explored. The response to glucose was linear up to 8.0 and 12.0 mM, and the sensitivities were 7.7+/-0.1 and 19.1+/-0.2 mA M(-1) cm(-2), respectively. The current response of the biosensors does not significantly change for 15 consecutive days in batch and for 10 days in flow, at least, if stored at 4 degrees C in phosphate buffer, when not in use. The effects of interferants and applicability to fruit juices and soft drinks analysis of the biosensor were also investigated.