Procedures are described for the deoxygenation of pure liquids, liquid mixtures and solutions of solids in liquids using tris(2,2′-bipyridyl)cobalt(II) perchlorate {[Co(bpy)3](CIO4)2} and sodium tetrahydroborate (NaBH4) in a colour-indicating reaction. The efficiency of the procedures is assessed by reference to the 1H spin-lattice relaxation times of a variety of materials. The values obtained show that the procedures are efficient, reproducible and time saving.