This paper deals with the problem of mass transfer representation within heterogeneous systems. For the purpose of their modelling from material balances, it is emphasised the existence of a well-suited change of state variables which leads to a representation containing a minimal number of parameters. The benefits of the proposed approach are illustrated by an example of parameter estimation performed from experimental breakthrough curves in chromatography. Experimental data concerning the adsorption of p-nitrophenol onto granular activated carbon are taken from [Chem, J., Chien, Y. (2002). Adsorption of nitrophenol onto activated carbon: isotherms and breakthrough curves. Water Research 36, 647-655]. This representation has several advantages: from a numerical point of view for simulation and also for parameter estimation since the number of parameter groups (macro-parameters) is minimal. In order to confirm the relevance of the change of coordinates that we propose, a structural identifiability study is also performed in some cases. (c) 2005 Elsevier Ltd. All rights reserved.