In the present work we have synthesized, magnesium ferrite, zinc ferrite, and magnesium zinc ferrite solid solutions using an economic wet chemical synthesis route. To understand the phase formation behavior of the synthesized powders, infra-red spectroscopy in conjunction with X-ray Rietveld refinement analyses has been performed. The structural characteristics of these ferrite powders are correlated with their room temperature magnetic properties. Phase pure, low temperature synthesized magnesium zinc ferrite nano-particles are investigated in terms of carbon monoxide and hydrogen gas sensing properties. The response and recovery transients of conductance are modeled using Langmuir adsorption kinetics with two active sites in the sensing elements used as CO sensors. For these two adsorption sites the activation energies for response and recovery behavior, estimated from the temperature dependence of respective time constants are found to be different. The difference in respective activation energies for response as well as recovery is thought to be due to different chemi-adsorbed oxygen species in these two sites. (C) 2009 Elsevier B.V. All rights reserved.