IL7 is a hematopoietic growth factor required for development and maintenance of lymphocytes including T cells, B cells, and natural killer cells. Recently, chicken IL7 (chIL7) has been cloned and studied in viral and parasite infection models. However, no monoclonal antibodies (mAb) that specifically detect chIL7 have been developed so far. In this study, recombinant chIL7 that expressed for immunization and mAb against chIL7 were developed and characterized to assess their immunologic properties. Five mAb exhibiting specific binding to chIL7 were generated and investigated for their applicability by Western blot, ELISA, and neutralization assays. A sandwich ELISA mAb pair that enables the measurement of chIL7 protein levels in biological samples from Eimeria-infected chickens was identified and several mAb neutralized chicken primary thymocyte proliferation mediated by chIL7. The mAb developed in this study will be valuable reagents for fundamental and applied immunological studies in poultry.