A large number of applications in industrial domains are concerned to slow processes, including flow, pressure, temperature and level control. Synthesis and control of such applications in the presence of uncertainty have been studied by many authors in recent decades. In this paper, a robust flow controller has been designed using H techniques to define and regulate the flow of pipe. The most robust method is synthesized using a state-space approach by taking into account the structured (parametric) perturbations in the plant coefficients. The proposed approach ensures internal stability, satisfying both frequency and time domain requirements, and obtaining minimal performance H -norm of the closed-loop system. The simulations are carried out using MATLAB and the results are compared with the classical PID, linear–quadratic–Gaussian and H ₂ methods, and they indicate that the overall system output performance can be improved using the proposed H robust controller.