  The recurrent nova RS Oph underwent a new outburst on August 8, 2021,
reaching a visible brightness of V = 4.8 mag. Observations of the 2021 outburst
made with the high resolution UVES spectrograph at the Kueyen-UT2 telescope of
ESO-VLT in Paranal enabled detection of the possible presence of 7Be freshly
made in the thermonuclear runaway reactions. The 7Be yields can be estimated in
N(Be)/N(H) = 5.7 x 10^(-6), which are close to the lowest yields measured in
classical novae so far. 7Be is short-lived and decays only into 7Li. By means
of a spectrum taken during the nebular phase we estimated an ejected mass of
about 1.1 x 10^(-5) Msun, providing an amount of about 4.4x 10^(-10) Msun of
7Li created in the 2021 event. Recurrent novae of the kind of RS Oph may
synthesize slightly lower amount of 7Li per event as classical novae, but occur
10^3 times more frequently. The recurrent novae fraction is in the range of
10-30% and they could have contributed to the making of 7Li we observe today.
The detection of 7Be in RS Oph provides further support to the recent
suggestion that novae are the most effective source of 7Li in the Galaxy.
