Fispact-II is an inventory code capable of performing modelling of activation, trans- mutations and burn-up induced by neutron, proton, alpha, deuteron or gamma parti- cles incident on matter. It is a completely new inventory code initially designed to be a functional replacement for Fispact-2007, but now extended to have substantially more capability. Fispact-II is written in object fortran and has full dynamic memory allocation. It has improved algorithms for the ode solver, pathways, uncertainty and sensitivity calculations. All these can be used in multi-pulse irradiation calculations, including those where the flux spectrum changes from pulse to pulse. It can now read ENDF- style data libraries in addition to the EAF libraries, and the present version uses the latest TALYS-based TENDL-2011, TENDL-2012 and TENDL-2013 evaluated nuclear data libraries together with probability table data from CALENDF for including self- shielding in the calculations. These libraries allow additional projectiles and nuclides to be included, and make possible additional kerma, dpa and appm diagnostics. This document is its User Manual. It first outlines what calculations the code performs and how the code differs from Fispact-2007. It has a ‘getting-started’ section to provide a basic introduction to new users. It explains the use and provides examples of all the keywords used in the input file to specify a Fispact-II run and describes how all the data files are connected. It introduces the test cases provided with the code and gives a guide to interpreting the physical output and logging output from the code. It also introduces subsidiary programs for printing output and for compressing the ENDF cross-section libraries. Three appendices are provided; the first outlines the physical and mathematical models implemented in the code. The second summarises the EAF nuclear data used by the code, giving background information on the data files and examples of neutron spectra suitable for various applications. The final appendix describes the ENDF data forms introduced in Version 2 of the code.