Design and performance of two atomic hydrogen masers constructed a t the National Research Council, Ottawa, Canada, are discussed. Measurements are given of the relative stability of the two masers for periods from 10 sec to 3 weeks, and the maser frequencies related to that of the NRC long cesium beam frequency standard over a 41 day period. The latter measurements are related to other cesium frequency standards in the United States and Canada. The best stability for a single maser was found to be about 1 Y 10-14 for averaging periods of 1 h over a 24 h period.* To be published.