Two　emerging　material　classes　are　combined　in　this　work,　namely　polymeric　carbon　nitrides　and　microporous　polymer　networks.　The　former,　polymeric　carbon　nitrides,　are　composed　of　amine-bridged　heptazine　moieties　and　showed　interesting　performance　as　a　metal-free　photocatalyst.　These　materials　have,　however,　to　be　prepared　at　high　temperatures,　making　control　of　their　chemical　structure　difficult.　The　latter,　microporous　polymer　networks　have　received　increasing　interest　due　to　their　high　surface　area,　giving　rise　to　interesting　applications　in　gas　storage　or　catalysis.　Here,　the　central　building　block　of　carbon　nitrides,　a　functionalized　heptazine　as　monomer,　and　tecton　are　used　to　create　microporous　polymer　networks.　The　resulting　heptazine-based　microporous　polymers　show　high　porosity,　while　their　chemical　structure　resembles　the　ones　of　carbon　nitrides.　The　polymers　show　activity　for　the　photocatalytic　production　of　hydrogen　from　water,　even　under　visible　light　illumination.　Heptazine-based　microporous　polymer　networks　(HMPs)　are　synthesized　by　room　temperature　polycondensation　of　cyameluric　chloride　with　aromatic　diamines.　Polymer　networks　with　significant　surface　area　and　pore　volume　are　obtained.　HMPs　are　active　and　stable　photocatalysts　for　the　production　of　hydrogen　from　water,　even　under　visible　light　irradiation.　Copyright　©　2013　WILEY-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim.