The first study of φ -meson production in p–Pb collisions at forward and backward rapidity, at a nucleon–nucleon centre-of-mass energy √s NN = 5 . 02 TeV, has been performed with the ALICE apparatus at the LHC. The φ -mesons have been identified in the dimuon decay channel in the transverse momentum (p T) range 1 <p T <7 GeV / c, both in the p-going (2 . 03 <y <3 . 53) and the Pb-going ( − 4 . 46 <y <− 2 . 96) directions — where y stands for the rapidity in the nucleon–nucleon centre-of-mass — the integrated luminosity amounting to 5 . 01 ± 0 . 19 nb − 1 and 5 . 81 ± 0 . 20 nb − 1 , respectively, for the two data samples. Differential cross sections as a function of transverse momentum and rapidity are presented. The forward–backward ratio for φ -meson production is measured for 2 . 96 <| y | <3 . 53, resulting in a ratio ∼ 0 . 5 with no significant p T dependence within the uncertainties. The p T dependence of the φ nuclear modification factor R pPb exhibits an enhancement up to a factor 1.6 at p T =