The ALICE experiment at the LHC was taking data in proton-proton collisions at the center-of-mass energy of 7 TeV starting from March till the end of October 2010. First heavy-ion collisions were delivered during November 2010. Among other particles, charmed and beauty mesons can be reconstructed by the ALICE apparatus. Open heavy flavour mesons provide a powerful tool to study hot quark matter produced in high energy heavy-ion collisions because their spectra are expected to be affected by energy loss in the medium. Measuring such particles is important also in proton-proton collisions. In this case they provide a necessary reference for heavy-ion collisions and allow to test pQCD predictions in a new energy domain. Different ways to reconstruct D and B mesons are described together with adopted selection and analysis techniques. D mesons in the central rapidity region are reconstructed via 2,3, and 4-prongs hadronic decays and via single electrons. In the forward region, semi-muonic decays are used to measure the production of D and B mesons. The first results for D mesons, single electrons and single muons are reported.