Experiments on the use of vortex ring transport for the mixing and de-stratification of liquids are described. The experiments were conducted using tube (chimney) type vortex ring mixers in rectangular and cylindrical mixing tanks having capacities of 1110L and 2000L respectively. The mixing experiments are primarily concerned with the mixing destratification of hot/cold water systems. Also the results of computer modelling of the transport of vortex rings through a stratification layer with Reynolds number of 1352, 4465 and 13 520 and Richardson numbers of 0.0093 and 0.091 for a Prandtl number of 7.00 are reported. It is apparent that the penetration of a vortex ring and therefore the mixing or destratification of a liquid system are primarily dependent on the Richardson number and virtually indepedent of the Reynolds number. (A)