The paper concerns with formulae and calculations of a selected group of Key Performance Indicators (KPIs) for the main electricity transmission system in Oman. These include the following service quality, reliability, security, and financial indicators [1]: &#; System Average Interruption Frequency Index (SAIFI) &#; System Average Interruption Duration Index (SAID) &#; Customer Average Interruption Duration Index (CAIDI) &#; Average Interruption Time (AIT) &#; Overhead Lines Maintenance Cost Index (OHLMCI) &#; Substation Maintenance Cost Index (SSMCI) Results of the main transmission grid in Oman, over the last 3 years, are presented. The results are useful in indicating trends of the KPIs and determination of future targets to improve transmission system performance. The goal of presenting the paper at the GCC 09 is to open a discussion among transmission utilities in the Gulf region for the possibility of introducing common KPIs to evaluate system performance. This could provide an excellent opportunity to establish acceptable benchmarks of the proposed KPIs.