[en] Heavy ion charge-exchange reactions have great potential for probing spin-transfer strength in nuclei, provided beams of sufficient energy are used so that the reactions might be expected to be simple (one-step) in nature. Tests of reaction mechanisms have been carried out for two of the most favorable reactions, (⁶Li,⁶He) and (¹²C,¹²N). We have shown that the first reaction is mainly one-step in nature at 25 MeV/nucleon and above and have established a calibration curve relating cross sections to Gamow-Teller matrix elements. We have also shown that the second reaction is likely to be mainly one-step above about 50 MeV/nucleon. A (¹²C,¹²N) measurement on Fe targets was done recently, with the aim of determining astrophysically interesting Gamow-Teller strengths in Fe nuclei. (orig.)