We report the first search for the penguin-dominated process B-s(0) -> eta'X(s ()s() over bar) using a semi-inclusive method. A 121.4 fb-1 integrated luminosity gamma(5S) data set collected by the Belle experiment, at the KEKB asymmetric-energy e(+)e(-) collider, is used.
We observe no statistically significant signal and, including all uncertainties, we set a 90% confidence level upper limit on the partial branching fraction at 1.4 x 10(-3) for M(X-s (s) over bar) <= 2.4 GeV/c(2).