In a sample of 7.8 million J/psi decays collected in the Beijing Spectromet
er, the process J/psi --> gamma eta(c) is observed for live different eta(c
) decay channels: K+ K- pi(+)pi(-), pi(+)pi(-)pi(+)pi(-), K+/- K(s)(o)pi(-/
+) (with K-s(o) --> pi(+)pi(-)), phi phi (with phi-->K+K-) and K(+)K(-)pi(o
). From these signals, we determine the mass of eta(c) to be 2976.6+/-2.9 /- 1.3 MeV. Combining this result with a previously reported result from a
similar study using psi(2S)-->gamma eta(c) detected in the same spectromete
r gives m(eta c) = 2976.3 +/- 2.3 +/- 1.2 MeV. For the combined samples, we
obtain Gamma(eta c) = 11.0 +/- 8.1 +/- 4.1 MeV.