The fluorinations of tetrachloropyrimidine, 2,4,6-trichloropyrimidine and trichloro-s-triazine were carried out in sealed tubes with KF in presence of inert gas and then compared. The fluorinated derivatives C 4F xCl yN 2 with x + y = 4, 0⩽x<4 , C 4HF xCl yN 2 with x + y = 3, 0⩽x⩽3 and C 3F xCl yN 3 with x + y = 3, 0⩽x⩽3 were obtained. The influence of contact time, temperature and concentration of the ion F − were investigated and compared; the molar yields were found to be always higher than 50% in our experimental conditions. We compare with the fluorinations of 2, 4 and 4, 6-dichloropyrimidine. It is possible to obtain directly, in good proportions, such fluorinated derivatives as 5-chlorotrifluoropyrimidine, trifluoropyrimidine and others. At high temperature (400°C for 16 h), tetrachloropyrimidine, in presence of KF, gave products of pyrolysis and condensation such as the fluorinated derivatives of C 6Cl 6 and C 5Cl 5N : C 6FCl 5, C 6F 2Cl 4 ··· or C 5FCl 4N, C 5F 2Cl 3N ···