The　magnetic　transition　has　been　studied　in　Mn1.1Fe0.9P0.8Ge0.2　by　magnetic　measurements　and　Fe-57　Mossbauer　spectroscopy.　The　alloy　crystallizes　in　the　hexagonal　Fe2P-type　structure　with　lattice　constants　of　a=6.0476(4)　angstrom　and　c=3.4766(7)　angstrom.　Both　bulk　magnetization　measurements　and　Mossbauer　spectroscopy　show　that　the　as-prepared　sample　has　a　significantly　lower　transition　temperature　on　first　cooling　(T-C(1)approximate　to　200　K)　than　after　it　has　undergone　thermal　cycling　to　20　K　(T-C(20)　(K)=240　K).　The　behavior　of　the　material　stabilizes　after　the　first　cooling/heating　cycle　and　no　further　changes　are　observed　in　T-C.　Working　with　a　stabilized　sample,　we　find　that　the　temperature　dependence　of　the　hyperfine　field,　B-hf(T),　is　more　rapid　than　that　predicted　by　a　simple　mean　field　Brillouin　function,　and　in　addition,　B-hf(T)　shows　a　thermal　hysteresis　of　10　K　upon　cooling　versus　heating.　These　results　show　that　the　magnetic　transition　at　T-C　is　definitely　first　order　and　suggest　that　there　is　an　additional　irreversible　magnetostructural　change　during　the　first　cooling　process　of　the　as-prepared　sample.　(C)　2009　American　Institute　of　Physics.　[DOI:　10.1063/1.3067496]