A binary composition of 1,3,3,3-tetrafluoropropene and ammonia, as well as to the use thereof, in particular as a heat-transfer fluid. The composition may include from 40% to 99% of ammonia and from 1% to 60% of 1,3,3,3-tetrafluoropropene; preferably from 60% to 98% of ammonia and from 2% to 40% of 1,3,3,3-tetrafluoropropene; preferably from 70% to 95% of ammonia and from 5% to 30% of 1,3,3,3-tetrafluoropropene; preferably from 75% to 90% of ammonia and from 10% to 25% of 1,3,3,3-tetrafluoropropene; preferably from 78% to 85% of ammonia and from 15% to 22% of 1,3,3,3-tetrafluoropropene. The 1,3,3,3-tetrafluoropropene may be in the cis form or in the trans form or is a mixture of cis form and trans form and in which, preferably, at least 80% or at least 90% or at least 95% or at least 98% or at least 99% of the 1,3,3,3-tetrafluoropropene is in the trans form.