X-ray spectroscopic measurements on light kaonic atoms are fundamental tool for the investigation of the low-energy quantum chromodynamics (QCD) in the strangeness sector, being a direct probe of the kaon-nucleus interaction at threshold without the need of an extrapolation at low energy as in the case of scattering experiments. In this framework, after the successful measurement of the kaonic hydrogen X-ray transition to the fundamental level in 2009, the SIDDHARTA-2 Collaboration is now ready to perform the first measurement of kaonic deuterium 2p -> 1s transitions, planned for 2021 – 2022 at LNF-INFN. This paper describes the SIDDHARTA-2 scientific case and the experimental apparatus installed in its reduced form called SIDDHARTINO at the DAΦNE collider, during the preparatory run before the kaonic deuterium data taking campaign.

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