Abstract: A process for the production of 3-hydroxy-1,3,5(10)-estratrien-17-one by pyrolysis of 1,4-androstadiene-3,17-dione in the presence of 1,2,3,4-tetrahydronaphthalene as hydrogen donor is described, by 1,2,3,4-tetrahydronaphthalene, preheated to a temperature of 450.degree.-850.degree. C., in a mixing zone being mixed with a solution, heated to a temperature of up to 300.degree. C., of 1,4-androstadiene-3,17-dione, in 1,2,3,4-tetrahydronaphthalene, the mixture being heated in a pyrolysis zone at a retention time of 0.001 to 60 seconds to temperatures of 450.degree.-700.degree. C. and the product leaving the pyrolysis zone being cooled off, which is characterized in that the pyrolysis is performed under a pressure of 3.5.times.10.sup.6 to 3.times.10.sup.8 Pa.