  The masses and the leptonic decay constants of vector and axial vector
heavy-heavy mesons are calculated using the thermal QCD sum rules approach.
While obtaining the QCD sum rules, additional operators in the Wilson expansion
and also temperature dependency of the continuum threshold are taken into
account. The masses and the decay constants remained unchanged up to
$T\simeq100~MeV$. After that point, they start to diminish. At the critical
temperature, the masses decreased about $3\%$, $5\%$ and $14\%$ for the vector
mesons $\Upsilon$, $B_{c}$ and $J/\psi$; $6\%$, $7\%$ and $22\%$ for the axial
vector mesons $\chi_{b1}$, $B_{c}$ and $\chi_{c1}$, respectively. The decay
constants reached about less than $20\%$ of their vacuum values. The obtained
results of the thermal mass and decay constant calculations at zero temperature
are in a very good agreement with the other non-perturbative calculations at
vacuum as well as with the experimental data.
