Maddox, NFrank, B.SBlyth, S.L2021-06-092021-06-092021Maddox, N. et al. (2021). MIGHTEE-HI: The H » i emission project of the MeerKAT MIGHTEE survey. Astronomy and Astrophysics, 646,A350004636110.1051/0004-6361/202039655http://hdl.handle.net/10566/6270We present the H » I emission project within the MIGHTEE survey, currently being carried out with the newly commissioned MeerKAT radio telescope. This is one of the first deep, blind, medium-wide interferometric surveys for neutral hydrogen (H » I) ever undertaken, extending our knowledge of H » I emission to z  =  0.6. The science goals of this medium-deep, medium-wide survey are extensive, including the evolution of the neutral gas content of galaxies over the past 5 billion years. Simulations predict nearly 3000 galaxies over 0  <   z  <   0.4 will be detected directly in H » I, with statistical detections extending to z  =  0.6. The survey allows us to explore H » I as a function of galaxy environment, with massive groups and galaxy clusters within the survey volume. Additionally, the area is large enough to contain as many as 50 local galaxies with H » I mass < 108 M⊙ , which allows us to study the low-mass galaxy population. The 20 deg2 main survey area is centred on fields with exceptional multi-wavelength ancillary data, with photometry ranging from optical through far-infrared wavelengths, supplemented with multiple spectroscopic campaigns. We describe here the survey design and the key science goals.enGalaxies: EvolutionGalaxies: Kinematics and dynamicsGalaxies: Star formationRadio lines: GalaxiesSurveysArticle