An intercomparison exercise for the African Dobson instruments took place in Irene, South Africa, in October and November 2009. Eight important instruments were involved in that exercise, including those from Cape Town, Springbok and Irene in South Africa, Maun in Botswana and Seychelles. Another four instruments, from Botswana, Kenya, Nigeria and Seychelles, took part in the extension of the exercise from 15 to 26 November 2009. All the participating instruments are now well calibrated and in good operational condition, except for that from Seychelles, which has a marginal calibration error and may need better expert attention before the next intercomparison event, which is scheduled to take place in 2014 or 2015. In addition, as another extension of the calibration campaign, an instrument from Cairo was calibrated in Germany in May 2010.