The use of MALDI-TOF mass spectrometry with fullerene matrices in the characterisation of insoluble, air-sensitive organolanthanides is described. The issues of matrix, sample preparation, fullerene stability, calibration, comparisons with other matrices, oxygen sensitivity and adduct formation of samples, radical chemistry, aggregation, the detection of triple-decker compounds, and complications in recording the spectra are discussed. The fullerene matrix is found to provide the basis for excellent characterisation for these compounds, and the technique is potentially of general utility.