Successful colour management of projection systems depends on knowledge of their characteristics. In this study, two typical portable projectors have been characterised. The two projectors are based on different technologies, Liquid Crystal Display (LCD) and Digital Light Processing (DLP). Measurements were made with a spectroradiometer.The LCD projector showed good colour additivity. The luminance difference between the sum of primaries and white was 0.33% after correction of the black level. The corresponding value for the DLP projector was 56%. This is due to a non-filtering segment in the filter wheel.The inter-channel dependency was calculated. The LCD projector showed good independence. For the DLP projector, the additional segment complicates the interpretation of the calculated values.Measurements of the signal input-output relationship have been made. The LCD projector showed a power function response, while the DLP projector showed an S-shaped response. Neither of these are native responses of the projectors, so this is probably a deliberate design.The chromaticity changes of primary colours and grey depending on the input signal were measured. The chromaticity constancy was poor for both projectors. It was shown that the relatively high black luminance is the dominant reason for this.The spatial uniformity was surprisingly poor. Measurements revealed uniformities down to 20% and 30% for the DLP and the LCD projector, respectively.Our tests showed that both the intensity and the colour of the background influenced the displayed colour. The average colour differences were found to be ΔE*_{a b}=4.83 for the LCD and ΔE*_{a b}=2.94 for the DLP projector.