  The results of a search for hydrogen-like atoms consisting of
$\pi^{\mp}K^{\pm}$ mesons are presented. Evidence for $\pi K$ atom production
by 24 GeV/c protons from CERN PS interacting with a nickel target has been seen
in terms of characteristic $\pi K$ pairs from their breakup in the same target
($178 \pm 49$) and from Coulomb final state interaction ($653 \pm 42$). Using
these results the analysis yields a first value for the $\pi K$ atom lifetime
of $\tau=(2.5_{-1.8}^{+3.0})$ fs and a first model-independent measurement of
the S-wave isospin-odd $\pi K$ scattering length
$\left|a_0^-\right|=\frac{1}{3}\left|a_{1/2}-a_{3/2}\right|=
\left(0.11_{-0.04}^{+0.09} \right)M_{\pi}^{-1}$ ($a_I$ for isospin $I$).
