The first measurement of groomed event shape observables in deep-inelastic electron-proton scattering (DIS) is presented.
The study is based on data collected with the H1 detector at HERA in the years 2003-2007 at the centre-of-mass energy $\sqrt{s} = 319\,\text{GeV}$.
The grooming techniques have been popular for jet substructure studies in hadron-hadron collisions, but have not been used in DIS before.
In this measurement, the grooming is performed in the Breit frame utilizing the Centauro jet clustering algorithm which is designed for DIS event topologies.
For events selected in the kinematic region of $Q^2 > 150\,\text{GeV}^2$ and $0.1 < y < 0.7$ the groomed 1-jettines and groomed invariant mass are measured considering three choices of the grooming parameter.
Several Monte Carlo predictions and analytical calculations are compared to the data.

