  The orbit and physical parameters of the previously unsolved double-lined
eclipsing binary Tyc 5227-1023-1, discovered during the search for RR Lyr
variables candidate members of the Aquarius stream, are derived using high
resolution \'echelle spectroscopy and $V$, $i^\prime$ photometry. Synthetic
spectral analysis of both components has been performed, yielding metallicity
[M/H] = $-0.63 \pm 0.11$ for both stars and the temperature of the secondary
which is in close agreement with the one from the orbital solution, while the
temperature of the primary is determined from photometry (T$_1 = 6350$ K). The
masses and radii ($M_1 = 0.96 \pm 0.02, M_2 = 0.84 \pm 0.01$ M$_{\odot}$, $R_1
= 1.39 \pm 0.01, R_2 = 0.98 \pm 0.01$ R$_{\odot}$) reveal that both stars have
already slightly evolved away from the Main Sequence band having an age of
about $7$ Gyr, and the results of synthetic spectral analysis support the claim
of co-rotation with the orbital motion. The radial velocity of the system is
$-60 \pm 2$ km sec$^{-1}$ while its distance, computed from orbital parameters
and the derived reddening $E_{B-V}$ = 0.053, is $496 \pm 35$ pc. Even though
Tyc 5227-1023-1 was initially treated as a possible member of the Aquarius
stream, the results presented here disagree with reported values for this
ancient structure, and suggest a likely membership of the thick disk.
