A “bench top” microcalorimeter has been designed and constructed. This instrument, and a more conventional microcalorimeter previously described, have been applied to several analytical determinations including both inorganic and enzymatic reactions. Because of the stability, yet rapid equilibration time of the bench top calorimeter, multiple analyses may be performed. The ease of operation, nearly universal applicability, and the possibility of obtaining thermodynamic as well as kinetic data simultaneously, make this technique extremely useful.