The　conformation,　aromaticity　and　gas-phase　acidity　(free　energy　of　deprotonation,　Delta　G　degrees)　of　3,4-dithiosquaric　acid　(3,4-dimercapto-3-cyclobutene-1,2-dione)　were　calculated　at　the　SCF　and　MP2　and　B3LYP　levels　using　6-311G　(d,　p)　and　6-311　+　G　(d,　p)　basis　sets.　The　global　minimum　found　on　the　potential　energy　surface　of　3,4-dithiosquaric　acid　presents　a　planar　conformation.　The　ZZ　isomer　was　found　to　be　the　most　stable　of　the　three　planar　conformers.　The　aromatic　stabilization　energy(ASE)　and　magnetic　susceptibility　exaltation　(Lambda)　were　also　computed　by　using　the　homodesmotic　reaction　and　RHF-CSGT　(Continues　Set　of　Gauge　Transformations)　and　RHF-IGAIM　(a　slight　variation　on　CSGT)　and　B3LYP-CSGT　(IGAIM)　methods　at　the　6-311　+　G(d,　p)　level.　The　calculated　ASE　and　Lambda　were　negative　values,　indicating　that　3,4-dithiosquaric　acid　is　aromatic.　Thus　the　titled　compound　fulfilled　the　geometrical,　energetic　and　magnetic　criteria　of　aromaticity.　The　most　reliable　theoretical　gas-phase　acidity　are　Delta　G(1,　298　K)degrees　=　1　295.4　kJ/mol　and　Delta　G(2,　298　K)degrees　=　1　691,　2　kJ/mol.