Abstract A new organic salt nonlinear optical crystal, l -arginine trifluoroacetate (LATF), has been grown from aqueous solutions. Growth morphology was deduced by the Bravais–Friedel Donnay–Harker (BFDH) model and the influence of pH value on crystal growth using the micro-crystallization method was studied. The results show that the growth properties could be improved by adding appropriate amount of HCl. Etch patterns on the {1 0 1} facet of LATF crystals are also illustrated and described.