  We use angle-resolved photoemission spectroscopy and full-potential
linearized augmented-plane-wave (FP-LAPW) calculations to study the electronic
structure of BaCo2As2. The Fermi surface (FS) maps and the corresponding band
dispersion data (at 90 K and 200 K) reveal a small electron pocket at the
center and a large electron pocket at the corner of the Brillouin zone.
Therefore the nesting between electron and hole FS pockets is absent in this
compound, in contrast to the parent compounds of FeAs-based high-T_c
superconductors. The electronic structure at about 500 meV binding energy is
very similar to features at the chemical potential in BaFe2As2. This indicates
that complete substitution of Co for Fe causes a nearly rigid shift in the
Fermi energy by adding two electrons per formula unit without significant
changes in the band dispersions. The experimental FS topology as well as band
dispersion data are in reasonable agreement with the FP-LAPW calculations.
