Crystal　structure,　magnetocaloric　effect　and　magnetic　transition　in　bulk　Mn1.1Fe0.9P0.8Ge0.2　compound　have　been　studied　by　X-ray　diffraction,　magnetic　measurements　and　Landau-Ginzberg　theory.　Mn1.1Fe0.9P0.8Ge0.2　compound　crystallizes　in　a　hexagonal　Fe2P-type　structure　with　lattice　constants　of　a　=　6.0789(10)　angstrom　and　c　=　3.4674(9)　angstrom.　The　compound　exhibits　giant　magnetocaloric　effect　with　maximum　magnetic　entropy　change　of　61.8　J/kg　K　in　a　field　change　from　0　to　5T　around　its　Curie　temperature　of　251　K.　The　temperature　dependence　of　the　Landau　coefficients　have　been　derived　by　fitting　the　magnetization　with　the　Landau　expansion　of　the　magnetic　free　energy,　indicating　the　first-order　nature　of　the　magnetic　transition　between　ferromagnetic　and　paramagnetic　states　in　the　compound.　(C)　2009　Elsevier　B.V.　All　rights　reserved.