The pure rotational spectra of CH 2DI and CHD 2I have been measured by microwave Fourier transform spectroscopy, millimeterwave spectroscopy and submillimeterwave spectroscopy. The quadrupole hyperfine structure due to iodine has been analyzed by direct diagonalization of the quadrupole tensor. For the J = 1–0 transition of the ground state of CH 2DI, the quadrupole hyperfine structure due to deuterium could be resolved and the quadrupole coupling constant eQq aa(D) determined. Accurate rotational and centrifugal distortion constants (up to sextic terms) have been determined. They are compared to the constants derived from the ground state combination differences (GSCD). A good agreement is observed but it is also found that the two kinds of data (GSCD and microwave) are complementary and a combined fit allows us to significantly improve the accuracy of the constants.