We present the WeCAPP catalogue of variable stars found in the bulge of M31 citep{wecapp05}. Observations in the WeCAPP microlensing survey (optical R and I bands) for a period of three years (2000-2003) resulted in a database with an excellent time coverage. We detected 23781 variable sources in a 16.1arcmin × 16.6arcmin field centered on the nucleus of M31. The catalogue of variable stars gives the positions, the periods, and the variation amplitudes in the R and I bands. We classified the variables according to their position in the R-band period-amplitude plane. Three groups can be distinguished; while the first two groups can be mainly associated with Cepheid-like variables (population I Cepheids in group I; type II Cepheids and RV Tauri stars in group II), the third one consists of Long Period Variables (LPVs). We detected 37 RV Tauri stars and 11 RV Tauri candidates, which makes this catalogue one of the largest collections of this class of stars to date. The classification scheme is supported by Fourier decomposition of the light curves. Our data shows a correlation of the low-order Fourier coefficients Phi 21 with Phi 31 for classical Cepheids, as well as for type II Cepheids and RV Tauri stars.