The first selenosquarato complex bis(tetraphenylphosphonium)[bis(1,2-diselenosquarato)palladate(II), (Ph 4 P) 2 [Pd(dssq) 2 ], crystallizes in the monoclinic spacegroup P2 1 /n with the unit cell parameters a = 11.0389(2) 9, b = 15.2791(2) 9, c = 14.7494(2) 9 and β = 95.2470(10) o . The complex can be obtained by the reaction of potassium 1,2-diselenosquarate (K 2 dssq) with potassium tetrachloropalladate (K 2 PdCl 4 ) under an argon atmosphere in deoxygenized water and precipitation by large cations (e.g. tetraphenylphosphonium).