This study is concerned with improving performance of composite structures through the use of adhesive bonding, particularly for marine and underwater applications. Some preliminary results from tests on simple composite/composite assemblies are given first. Difficulty in modelling the failure of even these simple joints highlighted the need for more reliable constituent input data. The first objective was to define an experimental methodology enabling the adhesives of interest to be characterised up to failure. A metal metal assembly was considered, in order to concentrate on the analysis of the behaviour of thin adhesive films. The aims were to characterise the adhesive, analyse its non-linear behaviour, and study the influence of parameters such as film thickness and manufacturing conditions. In order to be able to study the behaviour of the adhesive as a function of the normal stress component, an important parameter, a modified Arcan fixture has been developed, which enables compression or tension to be combined with shear loads. First results from this fixture are presented, together with analysis of sources of scatter in results.