Within the framework of the MPX-ATLAS collaboration a network of 15 Medipix2-based devices (MPX-ATLAS devices) has been installed at various positions in the ATLAS detector. The aim of the network is to perform real-time measurement of spectral characteristics and composition of radiation inside the ATLAS detector during its operation. This contribution is focused on the determination of the neutron component of the mixed radiation field. To identify different types of neutrons the 300 µm thick silicon sensor area of each MPX-ATLAS device is divided into several regions covered by different neutron converter materials. A 6LiF layer is used for thermal neutron detection and polyethylene foil for fast neutron detection. The calibration of all devices with known neutron sources (252Cf, AmBe, thermal neutrons, Van de Graaff accelerator beam) was performed in order to determine the detection efficiencies of all regions for different neutron energies. Using these calibrations it is possible to estimate spectral composition of unknown neutron field by comparing the responses from different regions of the MPX-ATLAS detector.