We have used a non-aqueous route to prepare capped, soluble MnFe2O4 nanoparticles of different sizes in order to understand the size-dependence of magnetic properties. As a result of the higher reaction temperatures (approaching 300 degreesC), the samples are more crystalline and display much larger saturation magnetization values compared with samples prepared by lower-temperature aqueous routes. The low-temperature saturation of the magnetization with field is also flatter for the capped particles. However, blocking temperatures remain comparable with those of samples prepared by aqueous means. Our results, compared with published magnetic data on uncapped particles, suggest that capping might help decrease the thickness and influence of the magnetic 'deadlayer' on the surface of the particle. (C) 2004 Published by Elsevier B.V.