  Leading order (in $\alpha_s$) perturbative QCD and power ($1/m_b^2)$
corrections to the hadronic invariant mass and hadron energy spectra in the
decay $B \to X_s \ell^+ \ell^-$ are reviewed in the standard model using the
heavy quark expansion technique (HQET). In particular, the first two hadronic
moments $<S_H^n>$ and $<E_H^n>$, $n=1,2$, are presented working out their
sensitivity on the HQET parameters $\lambda_1$ and $\bar{\Lambda}$. Data from
the forthcoming B facilities can be used to measure the short-distance
contribution in $B \to X_s \ell^+ \ell^-$ and determine the HQET parameters
from the moments $<S_H^n>$. This could be combined with complementary
constraints from the decay $B \to X \ell \nu_\ell$ to determine these
parameters precisely.
