The high spin states in neutron-rich 104Nb have been investigated from study of prompt γ-rays in spontaneous fission of 252Cf with the Gammasphere detector array. A new rotational band has been identified for the first time. This band is proposed as a semi-decoupled band based on the configuration π5/2-[303]ν1/2-[541]. The high spin states in neutron-rich 104Nb have been investigated from prompt of γ-rays in spontaneous fission of 252Cf with the Gammasphere detector array. A new rotational band has been identified for the first time. This band is proposed as a semi- decoupled band based on the configuration π5 / 2- [303] ν1 / 2- [541].