  We use x-ray absorption spectroscopy to investigate the local structure and
electronic properties of bulk La$_{1-y}$Sr$_{y}$Co$_{1-x}$Nb$_x$O$_3$ ($y=$
2$x$ as LSCNO and $y=$ 0 as LCNO) samples. The x-ray absorption near-edge
spectra (XANES) of LSCNO at Co K-edge affirm the valence state of Co in 3+.
However, in the case of the LCNO, a subtle variation in the valence state of Co
ions from 3+ to 2+ is evident with Nb substitution. The detailed analysis of
the Fourier transform (FT) of the extended x-ray absorption fine structure
(EXAFS) for the LSCNO samples exhibit the two groups of the bond-lengths owing
to the Jahn-Teller (JT) distortion in the CoO$_6$ octahedra, which manifest
that the Co$^{3+}$ ions exist in the intermediate spin-state
(t$^5_{2g}$e$^1_g$) at room temperature. However, we find that the JT
distortion is not present in LCNO samples for $x>$0.025 due to an increase in
the high-spin Co$^{2+}$/Co$^{3+}$ ions accompanied by the Nb--induced
structural transformation. Intriguingly, the La L$_3$-edge spectra for the
LSCNO samples exhibit that the La ions exist in the trivalent state and the
local disorder around La atoms decreases with Sr and Nb substitution.
Interestingly, the simulated FT of the EXAFS spectra at the La L$_3$-edge
demonstrates the three groups of La--O bond lengths, which exhibit a monotonous
change with Sr and Nb substitution. Moreover, the XANES measured at Sr and Nb
K-edges confirm their oxidation state to be in 2+ and 5+, respectively.
