We present results of a timing analysis of various isolated pulsars using ESAs emph{XMM-Newton} observatory. Isolated pulsars are useful for calibration purposes because of their stable emission. We have analyzed six pulsars with different pulse prof
iles in a range of periods between 15 and 200 ms. All observations were made using the emph{EPIC-pn camera} in its faster modes (Small window, Timing and Burst modes). We investigate the relative timing accuracy of the camera by comparing the pulse periods determined from the emph{EPIC-pn camera} observations with those from radio observations. As a result of our analysis we conclude that the relative timing accuracy of the emph{EPIC-pn camera} is of the order of $1times 10^{-8}$.
