Abstract: A search for B(s)0 → KS0K∗(892)0 decays is performed using pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, collected with the LHCb detector at a centre-of-mass energy of 7 TeV. The Bs0 → KS0K∗(892)0 decay is observed for the first time, with a significance of 7.1 standard deviations. The branching fraction is measured to (formula presented.),at 90 % confidence level. All results are consistent with Standard Model predictions.[Figure not available: see fulltext.]