  We revise cosmological mass bounds on hadronic axions in low-reheating
cosmological scenarios, with a reheating temperature $T_{\rm RH}~\le 100$ MeV,
in light of the latest cosmological observations. In this situation, the
neutrino decoupling would be unaffected, while the thermal axion relic
abundance is suppressed. Moreover, axions are colder in low-reheating
temperature scenarios, so that bounds on their abundance are possibly loosened.
As a consequence of these two facts, cosmological mass limits on axions are
relaxed. Using state-of-the-art cosmological data and characterizing axion-pion
interactions at the leading order in chiral perturbation theory, we find in the
standard case an axion mass bound $m_a < 0.26$ eV. However, axions with masses
$m_a \simeq 1$ eV, or heavier, would be allowed for reheating temperatures
$T_{\rm RH} \lesssim 80$ MeV. Multi-eV axions would be outside the mass
sensitivity of current and planned solar axion helioscopes and would demand new
experimental approaches to be detected.
