A measurement of the top quark pole mass m(t)(pole) in events where a top quarkantiquark pair (t (t) over bar) is produced in association with at least one additional jet ( t (t) over bar +jet) is presented. This analysis is performed using proton-proton collision data at root s = 13TeV collected by the CMS experiment at the CERN LHC, corresponding to a total integrated luminosity of 36.3 fb(-1). Events with two opposite-sign leptons in the final state (e(+) e(-), mu(+) mu(-), e(+/-) mu(-/+)) are analyzed. The reconstruction of the main observable and the event classification are optimized using multivariate analysis techniques based on machine learning. The production cross section is measured as a function of the inverse of the invariant mass of the t t +jet system at the parton level using a maximum likelihood unfolding. Given a reference parton distribution function (PDF), the top quark pole mass is extracted using the theoretical predictions at next-to-leading order. For the ABMP16NLO PDF, this results in m(t)(pole) = 172.93 +/- 1.36 GeV.