In this paper, as a first step, a comparison results of precipitable water vapour (PWV) data in Egypt derived from two techniques, radiosonde and Global Navigation Satellite Systems (GNSS) during a period of approximately 1 year (2014). Whereas radiosonde observations have a low temporal resolution and the observation interval is usually 12 h. GNSS can provide PWVs at a relatively high temporal resolution. Three of the GNSS stations were chosen nearby the radiosonde station(Al-Arish, Aswan, Marsa- Matrouh). These stations data processed by using the precise point positioning (PPP) service via a modernized CSRS-PPP service page to estimate the zenith tropospheric delay (ZTD). These stations were provided a representative regional distribution of GNSS sites with varying climates while ensuring conventional meteorological observations such as surface-based data are available for PWV conversion so as to be subsequently converted to GNSS-PWV. The results have shown that the Mean difference between PWVs from GNSS and radiosonde data are 2.89, 2.48and 0.6mm respectively.