Process for the manufacture of 1,2-dichloroethane starting with a hydrocarbon source according to which: a) the hydrocarbon source is subjected to cracking which produces a mixture of products containing ethylene and other constituents; b) the said mixture of products is separated into at least one fraction containing ethylene and into a heavy fraction (fraction C); c) the fraction or fractions containing ethylene are conveyed to a chlorination reactor and/or to an oxychlorination reactor, in which reactors most of the ethylene present is converted to 1,2-dichloroethane; d) the 1,2-dichloroethane obtained is separated from the streams of products derived from the chlorination and oxychlorination reactors and it is conveyed to the pyrolysis oven; and e) the fraction C is conveyed to cracking or to the oven for pyrolysis of 1,2-dichloroethane as fuel.