Context : The hard X-ray survey that Swift-BAT has been performing since late 2004 has provided a considerable database for a large number of sources whose hard X-ray emission was poorly known .

Aims : We are exploiting the BAT survey archive to improve the temporal and spectral characterization of the Galactic hard-X-ray sources .
In this letter we focus on the study of the high mass X-ray binary AX J1820.5–1434 .

Methods : All the data relevant to AX J1820.5–1434 have been extracted from the BAT survey archive and analyzed using a folding technique to search for periodical modulations .
A broad-band spectral analysis was also performed complementing the BAT spectrum with the available Swift-XRT and XMM-Newton pointed observations .

Results : A timing analysis has revealed the detection of a coherent signal at P _ { 0 } = 54.0 \pm 0.4 d , that we interpret as the orbital period of the binary system .
When folded with a period of P _ { 0 } , the light curve shows an asymmetric profile , with a minimum roughly consistent with zero intensity .
The broad band spectral analysis performed coupling Swift-XRT , XMM-Newton and Swift-BAT spectra confirms that the source emission is well modeled with a strongly absorbed power law with no evidence for a high energy exponential cutoff .

Conclusions :