The disclosure relates in its first aspect to a process of conversion of a gaseous stream comprising methane into hydrogen (51) and carbon (25), the process is remarkable in that it comprises a step (a) of providing a first gaseous stream (3, 7); a step (b) of bromination and synthesis in which the first gaseous stream (3, 7) is put in contact with a second stream (53) comprising bromine resulting in the formation of a third stream (15) comprising methyl bromides and hydrogen bromide, and of a fourth stream (25) comprising carbon including graphite and/or carbon black; a step (c) of separation performed on the third stream (15) to recover a hydrogen bromide-rich stream (41) which is then oxidized in a step (d) to produce a stream (51) comprising hydrogen. The second aspect relates to the installation for performing the process of the first aspect and the third aspect concerns the use of bromine in such process.