The possibility of supporting a saturated water vapour atmosphere together with the presence of liquid water in the Environmental Scanning Electron Microscope (ESEM) presents new opportunities for the observation of water-textile interactions. It is important to understand such interactions because they will affect many manufacturing and performance processes, including dyeing, finishing, comfort and washing behaviour. Control of temperature and pressure conditions surrounding the sample in the ESEM allows the performance of in situ hydration experiments at high magnification and resolution. Many organic materials are very susceptible to the effects of the beam in an electron microscope. Beam specimen interactions will change the nature and therefore behaviour of the sample. Experiments with cellulosic fibres showed that some of the visible signs of damage are identical to those indicating interaction with water. These signs include smoothing of the fibre surfaces, and loss of surface and edge detail. Experiments were performed to investigate the effect of various experimental parameters on the time of onset of damage. From the results of these experiments, conditions were found which delayed the onset of visible damage for 40-50 minutes. Using the damage-free conditions, mounting and hydration techniques were developed which allow the observation of cross-section area increase in fibres as they interact with liquid water. The results obtained for the lyocell fibres chosen for these experiments show good agreement with similar swelling experiments in the optical microscope performed to confirm the temperature independence of swelling at low temperature. The possibility of assessing the effect of packing density on swelling using the same hydration technique has also been investigated, but limitations of the mounting method prevent the acquisition of useful data for this purpose. A method has been developed for the observation of the wetting behaviour of various textile fabrics. It has been shown that the ESEM provides a quick and easy method of comparing the behaviours of sample materials. Ability to interpret the images produced in the microscope depends on a knowledge of wetting processes. Conditions have been found which allow the condensation of water droplets onto individual textile fibres. Initial assessment has been made to determine the suitability of the ESEM micrographs for the measurement of contact angles.