The polyseleno title compound, bis(N,N-diethylselenocarbamoyl) triselenide, [(Se(2)CNEt(2))(2)Se] or C(10)H(20)N(2)Se(5), is obtained from the disproportion of sodium N,N-diethyl-1,1-diselenocarbamate. An Se atom connects two N,N-diethyl-1,1-diselenocarbamate groups with Se-Se distances in the range 2.4500 (11)-2.8601 (12) A