Photo-catalysis　has　shown　a　prominent　and　eective　role　for　the　degradation　of　textile　dyes　and　organic　compounds　on　large　scale　to　keep　environment　and　water　reservoirs　clean　and　usable.　Photo-catalysts　produce　hydrogen　through　water　splitting　which　is　an　eco-friendly　source　of　renewable　energy.　Photo-catalysts　are　used　for　solar　cells　construction.　Photo-catalysis　generates　an　electron-hole　(e-h)　pair　due　to　light　interaction.　The　electron-hole　(e　-h　)　pair　produces　center　dot　OH　and　O　center　dot(2),　which　play　the　main　role　in　degradation　process;　it　leads　to　redox　reaction　and　oxidizes　organic　pollutants　to　H2O　and　CO2.　Major　causes　of　water,　air　and　soil　pollution　are　organic　pollutants,　heavy　metals　and　non-biodegradable　dyes　released　by　dierent　industries.　These　pollutants　especially　phenols　affected　dyes　have　seriously　aected　the　water　reservoirs.　This　paper　gives　a　critical　review　on　visible　and　solar　light　photo-catalysis　and　techniques　used　for　the　photo-degradation　of　hazardous　pollutants.　A　systematic　study　has　been　carried　out　from　the　published　literature　on　photo-degradation　of　organic　pollutants,　factors　eecting　the　photo-degradation　and　the　various　operating　parameters.　The　role　of　semiconductors/nano-catalysts　for　eco-friendly　renewable　energy　sources,　such　as　hydrogen　and　solar　cells　production　is　also　elaborated　for　future　energy　crises.　The　published　data　has　shown　that　different　parameters,　such　as　pH　of　the　system,　light　intensity,　catalyst　amount,　initial　concentration　and　amount　of　photo-catalysts　play　a　crucial　role　for　the　degradation　of　various　dyes　and　organic　pollutants.　Photo-catalysis　has　also　shown　significant　results　for　remediation　of　volatile　organic　pollutants　and　acid　gases　from　air.　This　review　has　focused　to　find　an　effient,　low　cost　and　result　oriented　photo-catalyst　and　the　effetive　environment　for　reaction.　The　concluded　data　has　shown　that　photo-catalysis　is　economically　suitable　and　fit　for　the　treatment　of　waste　water,　industrial　effuents　and　energy　production.