Single crystals of MnIn2SxSe4-x with 0.4 less than or equal to x less than or equal to 2.4 have been obtained by chemical transport reactions with iodine in the temperature gradient 860 --> 800 degrees C. Ohmic contacts to these crystals could be obtained by treatment of the crystals with hydrogen and/or indium at 400 degrees C. By this treatment the conductivity of the crystals, which are very poor conductors in the untreated state, are enhanced by at least 6 orders of magnitude. The samples are photoconductors with a photo sensitivity S = (sigma(p)-sigma(d))/sigma(d) between 1 and 10(-4), depending on the treatment of the crystals.