  We present a method for producing high quality KCo2As2 crystals, stable in
air and suitable for a variety of measurements. X-ray diffraction, magnetic
susceptibility, electrical transport and heat capacity measurements confirm the
high quality and an absence of long range magnetic order down to at least 2 K.
Residual resistivity values approaching 0.25 $\mu\Omega$~cm are representative
of the high quality and low impurity content, and a Sommerfeld coefficient
$\gamma$ = 7.3 mJ/mol K$^2$ signifies weaker correlations than the Fe-based
counterparts. Together with Hall effect measurements, angle-resolved
photoemission experiments reveal a Fermi surface consisting of electron pockets
at the center and corner of the Brillouin zone, in line with theoretical
predictions and in contrast to the mixed carrier types of other pnictides with
the ThCr2Si2 structure. A large, linear magnetoresistance of 200\% at 14~T,
together with an observed linear and hyperbolic, rather than parabolic, band
dispersions are unusual characteristics of this metallic compound and may
indicate more complex underlying behavior.
