These are chemical reactions that involve reduction and oxidation.

A chemical reaction is said to be a REDUCTION when there is

o   a loss of oxygen
o   a reduction in the oxidation number / state
o   a gain in hydrogen
o   a gain in electron(s).

A chemical reaction is said to be an OXIDATION when there is

o   a gain in oxygen
o   an increase in oxidation number / state
o   a loss of hydrogen
o   a loss of electron(s)
       
      

     
Tindak balas redoks melibatkan tindak balas kimia penurunan dan pengoksidaan.

Terdapat tindak balas PENURUNAN apabila berlakunya satu atau lebih daripada satu yang berikut

o   kehilangan oksigen
o   pengurangan nombor / keadaan pengoksidaan
o   penambahan hidrogen
o   penambahan elektron.

Tindak balas PENGOKSIDAAN berlaku dengan

o   penambahan oksigen
o   peningkatan nombor / keadaan pengoksidaan
o   kehilangan hidrogen
o   pengurangan elektron