The rotational cutoff levels of C2(B' 1-SIGMA-g+, v" = 1,2), produced in the multiphoton dissociation of jet-cooled acetylene at 193 nm, have been measured using laser-induced fluorescence. This data is used to calculate the values DELTA-H(f,0)(C2) = 194.8 +/- 0.5 kcal/mol and D0(CC-H) = 112.0 +/- 0.8 kcal/mol, in excellent agreement with the latest theoretical calculations.