Аннотация:The first observation of the Λ0b→D−sp decay is presented using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of s√=13TeV, corresponding to a total integrated luminosity of 6fb−1. Using the Λ0b→Λ+cπ− decay as the normalisation mode, the branching fraction of the Λ0b→D−sp decay is measured to be B(Λ0b→D−sp)=(12.6±0.5±0.3±1.2)×10−6, where the first uncertainty is statistical, the second systematic and the third due to uncertainties in the branching fractions of the Λ0b→Λ+cπ−, D−s→K−K+π− and Λ+c→pK−π+ decays.