The purpose of this study was to identify changes occurred during the process of particle coating in a spouted bed, by comparing data from visual observation along with the statistic and spectral analysis of data from pressure drop in real time. The experiments were carried out in a cone-cylindrical spouted bed, with ABS and polystyrene particles and with a polymeric Eudragit(R) based suspension. The pressure drop time series were collected with Labview 7.0 and turned into the frequency domain by using a fast Fourier transform routine. The dynamic changes observed during the coating process were paired with the power spectra, in order to create an identification procedure for the situations of low particles circulation rate, internal spout and bed collapse. Hopefully, an objective identification of instabilities may lead to a future application of process control. (C) 2009 Elsevier B.V. All rights reserved.