  AMS-02 is a wide acceptance high-energy physics experiment installed on the
International Space Station in May 2011 and it has been operating continuously
since then. AMS-02 is able to separate cosmic rays light nuclei ($1\leq Z \leq
8$) with contaminations less than $10^{-3}$. The ratio between the cosmic rays
Boron and Carbon fluxes is known to be very sensitive to the properties of the
propagation of cosmic rays in the Galaxy, being Boron a secondary product of
spallation on the interstellar medium of heavier primary elements such as
Carbon and Oxygen. A precise measurement reaching the TeV region can
significantly help understanding cosmic rays propagation in the Galaxy and the
amount of matter traversed before reaching Earth. The status of the measurement
of the boron-to-carbon ratio based on 10 millions Boron and Carbon events is
presented.
