When hydrogen is fitted into the reactivity series it comes after what ?

It depends on your list, how many elements are listed. Commonly, on tables of 15 elements, Hydrogen follows Lead. If your table does not include Lead, then Iron is probably one set above Hydrogen. But it depends on your list..how many metals are listed. Between Lead and Iron, are Cd, Co, Ni, Sn. Lead is probably what you are looking for.