  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$\rm _{ex}$=24$\pm$8$\,$K) and a warm (T$\rm _{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.
