In this paper, we present a result regarding the probability distribution of wavelets coefficients. It extends the Theorem 1 that is presented in our previous work-Cohen, A. et al. Design of experiments and statistical process control using wavelets analysis. Control Engineering Practice. 2015- to include Biorthogonal wavelets. Then, a new control chart, called OWave (Orthogonal Wavelets), is proposed in order to detect mean change in the process. The statistic of the proposed control chart is based on weighted wavelets coefficients. Performance study shows that OWave control chart performs slightly better than the optimal version of EWMA control chart. (C) 2016, IFAC (International Rderation or Automatic Control) Hosting by Elsevier Ltd. All rights reserved.