The data set contains daily files of path integrated amount of water vapour (precipitable water, prw) derived from the MiRAC-P (or LHUMPRO-243-340) microwave radiometer (see Mech et al., 2019) onboard the Polarstern during cruise PS122 (MOSAiC expedition). The data covers the range October 2019 to October 2020. MiRAC-P measures atmospheric radiation in six double side band averaged G band (183.31 +/- 0.6 to 183.31 +/- 7.5 GHz) and two higher frequency (243 and 340 GHz) channels. The different sensitivity to humidity of the channels allow a derivation of the path integrated amount of water vapour (prw). A Neural Network retrieval has been used to derive prw. The uncertainty of prw is given as the variable's comment attribute and describes the expected standard error. Prw is provided for all available times so that it is up to the user to decide whether or not to use the values if quality flags are set.