The production of K-S(0) mesons in pp collisions at a centre-of-mass energy of 0.9 TeV is studied with the LHCb detector at the Large Hadron Collider. The luminosity of the analysed sample is determined using a novel technique, involving measurements of the beam currents, sizes and positions, and is found to be 6.8 +/- 1.0 mu b(-1). The differential prompt K-S(0) production cross-section is measured as a function of the K-S(0) transverse momentum and rapidity in the region 0 < p(T) < 1.6 GeV/c and 2.5 < y < 4.0. The data are found to be in reasonable agreement with previous measurements and generator expectations. (C) 2010 Published by Elsevier B.V.