Chloromethane is the only organochloride detected in space to date. Its recent observation towards the low-mass protostar IRAS 16293-2422 with ALMA offers a prompt for new laboratory studies of CH 3 Cl and its isotopologues. Here, we report the investigation of the rotational spectrum of monodeuterated chloromethane CH 2 DCl in the frequency region between 90 and 300 GHz. The measurements have been carried out with a frequency-modulation millimeterwave spectrometer, arranged to perform saturation spectroscopy. From the analysis of hyperfine-resolved spectra of the two chlorine isotopologues CH 2 D 35 Cl and CH 2 D 37 Cl, consistent sets of accurate spectroscopic parameters have been obtained. This work provides reliable spectral predictions which can be used to guide radio-astronomical searches of CH 2 DCl in the interstellar medium and represents a solid base for future analyses of high-resolution infrared spectra of monodeuterated chloromethane.