Hydrogen generation from water is a clean energy source to address the challenges of climate change and sustainable energy solution. Water splitting consists of water oxidation to oxygen and proton, whereby proton can be reduced to clean hydrogen. The first part of this talk will be the discussion on electrochemical water oxidation and water reduction, by various heterogeneous catalysts. The water oxidation, catalyzed by a simple mononuclear cobalt(II)-aqua coordination complex, entrapped in the confined space of a metal organic framework (MOF) in a ‘ship in a bottle’ manner will be discussed first.1 When we place [Co(H2O)6]2+ coordination complex inside the zeolite-Y cages and deposit this zeolite-Y encapsulating hexa-aqua-Co(II) complex on a working electrode surface, this electrode on dipping in an alkaline aqueous solution forms nanofilm of α-Co(OH)2 on zeolite-Y surface. This nanofilm of α-Co(OH)2 acts an efficient catalyst for electrochemical water oxidation.2 The central element Co(II) of a Keggin anion [CoIIW12O40]6– is, as such, not catalytically active. This becomes an efficient electrocatalyst for water oxidation,3 when the relevant Keggin anion is encapsulated inside the well-defined confined space of the framework material ZIF-8. The same Keggin anion [CoIIW12O40]6– can act as support to attach a {Ni(bipy)2(H2O)}2+ complex on its surface through coordinate covalent bond via one of its terminal oxo groups and becomes an efficient (heterogeneous) water oxidation catalyst.4 Besides electrochemical water oxidation, we have demonstrated electrocatalytic hydrogen evolution reaction (HER) shown by an Anderson-type polyoxometalate supported Cu(H2O)(phen) complex, as an electrocatalyst.5 We have carried out detailed kinetic studies of all these electrocatalytic water oxidation and water reduction studies. The next part of this talk will be based on a fully reduced {V15}-type polyoxovanadate (POV) cluster system, which can capture aerial CO2 in its cavity in the form of carbonate. The entrapped carbonate can be excluded from the cavity of this POV cluster as CO2 in a gas-solid interface reaction.6 This fully reduced POV cluster system additionally exhibits excellent proton conductivity, important for fuel cell fabrication. At the last, UiO-66-based superprotonic conductor with the highest MOF-based proton conductivity, we recently achieved,7 will be mentioned.