In this work, the Infinite DimEnsionAl State-space (IDEAS) method and the associated Shrink-wrap algorithm are shown to be applicable to variable density fluid (VDF) reactor network synthesis (RNS). To this end, mathematical models for variable density fluid continuous stirred tank reactors (CSTR) and plug flow reactors (PFR) are shown to give rise to linear operators within the IDEAS framework. Using IDEAS, a variety of convex (linear) objective functions, such as maximization of concentration, yield, selectivity, or economic considerations like minimization of total reactor volume, or attainable region construction can be handled by linear programming. To demonstrate the effectiveness of the proposed method, three reactor network synthesis case studies involving gas phase reactions are presented. (c) 2006 Elsevier B.V. All rights reserved.