Abstract : Galileo Avionica S.p.A. (GA), Italy, is industrializing under the European Space Agency supervision a passive hydrogen maser (PHM), to be used in the GalileoSat constellation as master onboard clock. The Engineering Model (EM) phase is being completed under the lead of the Observatory of Neuchatel (ON, Switzerland) with the cooperation of GA and Temex Neuchatel Time (TNT, Switzerland). Current activity regards integration at ON of the EM electronics with the EM physics package. Tuning is in progress and preliminary results are good. Test completion is planned by the end of this year. The parallel industrialization activity, with GA leading the industrial consortium of the above-mentioned companies, is aimed at PHM design consolidation for future flight production. While GA produces the electronics and integrates the PHM, TNT with ON support produces the physics package. In this frame the EM design is being thoroughly reviewed in the scope of performance optimization and cost reduction, while keeping the critical performances unchanged.