A measurement of D meson production by the LHCb experiment in its fixed-target configuration is presented. The production of D mesons is studied with a beam of 2.5 TeV protons colliding on a gaseous neon target at rest, corresponding to a nucleon–nucleon centre-of-mass energy of sNN=68.5GeV . The sum of the D and D¯ production cross-section in pNe collisions in the centre-of-mass rapidity range y⋆∈ [- 2.29 , 0] is found to be σD0y⋆∈[-2.29,0]=48.2±0.3±4.5μb/nucleon where the first uncertainty is statistical and the second is systematic. The D- D¯ production asymmetry is also evaluated and suggests a trend towards negative values at large negative y⋆ . The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1 % intrinsic charm and 10 % recombination contributions better describe the data than the other models considered.