The neutron transport class library described here 
simulates the interactions of neutrons with kinetic energies 
from thermal energies up to O(20~MeV). The upper limit is set by
the comprehensive evaluated neutron scattering data libraries that the
simulation is based on.
The result is a set of secondary particles that can be passed on to the
tracking sub-system for further 
geometric tracking within {\sc Geant4}. 

The interactions of neutrons at low energies are split
into four parts in analogy to the other hadronic processes in {\sc Geant4}. 
We consider radiative capture, elastic scattering, fission, and 
inelastic scattering as separate models. These models
comply with the interface for use with the {\sc Geant4} hadronic processes
which enables their transparent use within the {\sc Geant4} tool-kit together with
all other {\sc Geant4} compliant hadronic shower models.
