In general, the flow rates of cooling water flowing in a heat exchangers network should be measured for its operational purpose. However, it is difficult to install flow meters on every spot because of the financial and technical reasons. This work presents an explicit algorithm for determining the flow rates of cooling water flowing in the heat exchangers network in the chemical plant. An algorithm is also presented to obtain the desired flow rates of cooling water in each heat exchanger. In order to solve this problem, multivariable optimization techniques will be used to minimize the differences between the desired flow rates and the present cooling water flow rates which flows through the heat exchanger. The commercial computer program GAMS/MINOS which solves the nonlinear optimization problem is used. Numerical examples are presented to illustrate the scope of this work which can be handled with the formulation.