Results are presented from a search for third-generation leptoquarks and scalar bottom quarks in a sample of proton-proton collisions at root s = 7TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.7 fb(-1). A scenario where the new particles are pair produced and each decays to a b quark plus a tau neutrino or neutralino is considered. The number of observed events is found to be in agreement with the standard model prediction. Upper limits are set at 95% confidence level on the production cross sections. Leptoquarks with masses below similar to 450 GeV are excluded. Upper limits in the mass plane of the scalar quark and neutralino are set such that scalar bottom quark masses up to 410 GeV are excluded for neutralino masses of 50 GeV.