Theories of a pre-RNA world suggest that glycolonitrile ( HOCH _ { 2 } CN ) is a key species in the process of ribonucleotide assembly , which is considered as a molecular precursor of nucleic acids . In this Letter , we report the first detection of this pre-biotic molecule in the interstellar medium ( ISM ) by using ALMA data obtained at frequencies between 86.5 GHz and 266.5 GHz toward the Solar-type protostar IRAS16293-2422 B . A total of 15 unblended transitions of HOCH _ { 2 } CN were identified . Our analysis indicates the presence of a cold ( T _ { ex } =24 \pm 8 K ) and a warm ( T _ { ex } =158 \pm 38 K ) component meaning that this molecule is present in both the inner hot corino and the outer cold envelope of IRAS16293 B . The relative abundance with respect to H _ { 2 } is ( 6.5 \pm 0.6 ) \times 10 ^ { -11 } and \geq ( 6 \pm 2 ) \times 10 ^ { -10 } for the warm and cold components respectively . Our chemical modelling seems to underproduce the observed abundance for both the warm and cold component under various values of the cosmic-ray ionisation rate ( \zeta ) . Key gas phase routes for the formation of this molecule might be missing in our chemical network .