Structural studies of three different SiCN bulk compounds were performed by neutron wide angle scattering in order to follow the influence of the polymer architecture on respective microstructure and the resistance to crystallization. The materials were found to be amorphous after treatment at 1000 and 1400degreesC. Total pair correlation function were calculated to describe the local arrangement of the different network with emphasis on the interatomic distances Si-N and Si-C. Few differences were observed between the specimens except for the relative ratio of C-C and Si-N bonds, the first feature being detected even at 1000degreesC. After heat treatment at higher temperature (1400degreesC), a slight structural ordering of the structures was observed, and few Si-C bonds could be detected by a careful comparison of the differential total pair correlation function curves.