The ab initio direct dynamics method at the G2//UQCISD/6-311 + G(d,p) level is employed to study the hydrogen abstraction reaction C-2((3)Pi (4)) + H-2 -> C2H + H over a wide temperature range 100-4650 K. The barrier heights obtained for the forward and reverse reactions are 7.78 and 17.53 kcal/mol, respectively. Comparing with one recent experiment, the calculated forward rate constants over the temperature range 2580-650 K are about 4.3-13.5 times greater and show a steeper temperature-dependent effect. This indicates that further experimental investigation on this simple radical reaction may still be desired. Finally, G(2)//UQCISD/6-311 + G(2df,2p) calculations are performed to test the reliability of the G2//UQCISD/6-311 + G(d,p) results.