The pT-differential inclusive production cross section of the prompt charm-strange meson Ds+ in the rapidity range |y|<0.5 was measured in proton-proton collisions at s=7 TeV at the LHC using the ALICE detector. The analysis was performed on a data sample of 2.98×108 events collected with a minimum-bias trigger. The corresponding integrated luminosity is Lint=4.8nb-1. Reconstructing the decay Ds+→φπ+, with φ→K-K+, and its charge conjugate, about 480 Ds± mesons were counted, after selection cuts, in the transverse momentum range 2<pT<12GeV/c. The results are compared with predictions from models based on perturbative QCD. The ratios of the cross sections of four D meson species (namely D0, D+, D*+ and Ds+) were determined both as a function of pT and integrated over pT after extrapolating to full pT range, together with the strangeness suppression factor in charm fragmentation. The obtained values are found to be compatible within uncertainties with those measured by other experiments in e+e-, ep and pp interactions at various centre-of-mass energies. © 2012 CERN.