  We have used archival Hubble Space Telescope observations obtained with the
Advanced Camera for Surveys to study the H{\alpha} emission properties of main
sequence stars in the globular cluster 47 Tucanae. Using a combination of
multi-band observations in the F606W, F814W and F658N bands, we search for
stars showing H{\alpha} excess emission. An accurate photometric measurement of
their H{\alpha} equivalent width allows us to identify objects with large
H{\alpha} emission, which we attribute to mass accretion rather than enhanced
chromospheric activity. The spatial position of some of these stars is
coincident with that of known X-ray sources and their location in the
colour-magnitude diagram allows us to classify them as active binaries or
cataclysmic variables (CVs). We show that this method, commonly adopted to
study accreting discs in young stellar objects, can be successfully used to
identify and characterise candidate CVs.
