A crystalline salt of L -lysine- d -amphetamine represented by the chemical structure as depicted in formula wherein n is in the range of from 1.9 to 2.1 and A is selected from the group consisting of adipic acid, p -toluene sulfonic acid, fumaric acid and oxalic acid, and wherein the crystalline salt ist selected from the group consisting of • L -lysine- d -amphetamine diadipate (form I), characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (4.7 ± 0.2)°, (11.1 ± 0.2)° and (18.9 ± 0.2)°, when measured at a temperature in the range of from 20 to 30 °C and a relative humidity in the range of from 0 to 65% with Cu-Kalpha 1,2 radiation having a wavelength of 0.15419 nm; • L -lysine- d -amphetamine diadipate (form II), characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (4.7 ± 0.2)°, (7.1 ± 0.2)° and (21.1 ± 0.2)°, when measured at a temperature in the range of from 20 to 30 °C and a relative humidity in the range of from 0 to 65% with Cu-Kalpha 1,2 radiation having a wavelength of 0.15419 nm; • L -lysine- d -amphetamine ditosylate (form I), characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (6.0 ± 0.2)°, (7.4 ± 0.2)° and (8.1 ± 0.2)°, when measured at a temperature in the range of from 20 to 30 °C and a relative humidity in the range of from 0 to 65% with Cu-Kalpha 1,2 radiation having a wavelength of 0.15419 nm; • L -lysine- d -amphetamine ditosylate (form II), characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (5.0 ± 0.2)°, (5.7 ± 0.2)° and (7.2 ± 0.2)°, when measured at a temperature in the range of from 20 to 30 °C and a relative humidity in the range of from 0 to 65% with Cu-Kalpha 1,2 radiation having a wavelength of 0.15419 nm; • L -lysine- d -amphetamine difumarate, characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (4.3 ± 0.2)°, (6.6 ± 0.2)° and (23.8 ± 0.2)°, when measured at a temperature in the range of from 20 to 30 °C and a relative humidity in the range of from 0 to 65% with Cu-Kalpha 1,2 radiation having a wavelength of 0.15419 nm; and • L -lysine- d -amphetamine dioxalate, characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (9.2 ± 0.2)°, (9.4 ± 0.2)°and (12.3 ± 0.2)°, when measured at a temperature in the range of from 20 to 30 °C and a relative humidity in the range of from 0 to 65% with Cu-Kalpha 1,2 radiation having a wavelength of 0.15419 nm. • L -lysine- d -amphetamine diadipate (form I), characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (4.7 ± 0.2)°, (11.1 ± 0.2)° and (18.9 ± 0.2)°, when measured at a temperature in the range of from 20 to 30 °C and a relative humidity in the range of from 0 to 65% with Cu-Kalpha 1,2 radiation having a wavelength of 0.15419 nm; • L -lysine- d -amphetamine diadipate (form II), characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (4.7 ± 0.2)°, (7.1 ± 0.2)° and (21.1 ± 0.2)°, when measured at a temperature in the range of from 20 to 30 °C and a relative humidity in the range of from 0 to 65% with Cu-Kalpha 1,2 radiation having a wavelength of 0.15419 nm; • L -lysine- d -amphetamine ditosylate (form I), characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (6.0 ± 0.2)°, (7.4 ± 0.2)° and (8.1 ± 0.2)°, when measured at a temperature in the range of from 20 to 30 °C and a relative humidity in the range of from 0 to 65% with Cu-Kalpha 1,2 radiation having a wavelength of 0.15419 nm; • L -lysine- d -amphetamine ditosylate (form II), characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (5.0 ± 0.2)°, (5.7 ± 0.2)° and (7.2 ± 0.2)°, when measured at a temperature in the range of from 20 to 30 °C and a relative humidity in the range of from 0 to 65% with Cu-Kalpha 1,2 radiation having a wavelength of 0.15419 nm; • L -lysine- d -amphetamine difumarate, characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (4.3 ± 0.2)°, (6.6 ± 0.2)° and (23.8 ± 0.2)°, when measured at a temperature in the range of from 20 to 30 °C and a relative humidity in the range of from 0 to 65% with Cu-Kalpha 1,2 radiation having a wavelength of 0.15419 nm; and • L -lysine- d -amphetamine dioxalate, characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (9.2 ± 0.2)°, (9.4 ± 0.2)°and (12.3 ± 0.2)°, when measured at a temperature in the range of from 20 to 30 °C and a relative humidity in the range of from 0 to 65% with Cu-Kalpha 1,2 radiation having a wavelength of 0.15419 nm.