A parametric study is presented to highlight design challenges of thermally integrated microchannel networks for portable chemistry and/or fuels reforming. One-dimensional modeling analysis of heat transfer in a two-fluid system is presented for the case of (i) two nonreacting fluids (heat exchanger), (ii) a single exothermic reacting fluid and a second nonreacting fluid (regenerative combustor), and (iii) one exothermic reacting fluid and a second endothermic reacting fluid (heat exchanger reactor). In each case, the influence of solid-phase thermal conductivity and thermal packaging upon thermal efficiency, reaction conversion, and steady-state multiplicity is investigated. Results demonstrate the importance of both packaging and solid-phase axial thermal conduction upon system performance, with optimal performance obtained using low thermal conductivity substrates. Modeling analysis predicts steady-state multiplicity when employing low thermal conductivity materials, illustrating the need for future detailed stability analysis. Lastly, simplified mechanical analysis is presented to illustrate the value of coupled thermomechanical analysis.