  We evaluate the mass of the $B_{s0}$ scalar meson and the coupling constant
in the $B_{s0} B K$ vertex in the framework of QCD sum rules. We consider the
$B_{s0}$ as a tetraquark state to evaluate its mass. We get $m_{B_s0}=(6.04\pm
0.08) \GeV$, which is bigger than predictions supposing it as a $b\bar{s}$
state or a $B\bar{K}$ bound state with $J^{P}=0^+$. To evaluate the $g_{B_{s0}B
K}$ coupling we use the three point correlation functions of the vertex,
considering $ B_{s0} $ as a normal $b\bar{s}$ state. The obtained coupling
constant is: $g_{B_{s0} B K} =(16.3 \pm 3.2) \GeV$. This number is in agreement
with light-cone QCD sum rules calculation. We have also compared the decay
width of the $\BS\to BK$ process considering the $\BS$ to be a $b\bar{s}$ state
and a $BK$ molecular state. The width obtained for the $BK$ molecular state is
twice as big as the width obtained for the $b\bar{s}$ state. Therefore, we
conclude that with the knowledge of the mass and the decay width of the $\BS$
meson, one can discriminate between the different theoretical proposals for its
structure.
