In a process for the production of ammonia synthesis gas from a hydrocarbon-containing feedstock, comprising steam reforming of the feedstock and treatment of the synthesis gas obtained, the shift of the synthesis gas comprises two shift steps, both including stable catalysts, whereby the formation of hazardous by-products is avoided or at least reduced to an acceptable low level. The two shift steps can both be HTS, or they can be one HTS and one LTS or one HTS and one MTS. The catalyst used in the HTS and the LTS steps is based on zinc oxide and zinc aluminum spinel, and the catalyst used in the MTS and the LTS steps can be based on copper.