C4H12N+.C5F4NO-, M(r) = 240.2, triclinic, P1BAR, a = 9.268 (6), b = 9.637 (7), c = 7.209 (4) angstrom, alpha = 107.06 (5), beta = 95.22 (5), gamma = 63.70 (4)-degrees, V = 551.3 (7) angstrom 3, Z = 2, D(x) = 1.45 Mg m-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 0.13 mm-1, F(000) = 248, T = 293 K, R = 0.049 for 1455 unique reflexions [F greater-than-or-equal-to 3-sigma(F)]. The title compound, H2NEt2+.NC5F4O-, forms as an unexpected by-product during the synthesis of N,N-diethyl-O-(tetrafluoro-4-pyridyl)-hydroxylamine. Strong hydrogen bonds link two anion/cation pairs into a cyclic centrosymmetric dimer [N...O 2.741 (8), 2.765 (7); H...O 1.60 (6), 2.08 (6) angstrom; N-H...O 172 (5), 161 (7)-degrees], which may in part explain the salt's stability and hence ease of formation.