The ISEMMS project aims at the development of an integrated energy and maintenance management system to optimise the energy efficiency and minimise the maintenance cost of ship machinery systems by monitoring of the performance, emissions and plant condition parameters, culminating in proposing the most effective energy and maintenance scheduling. A number of advanced technologies including model based power management and fault diagnosis, condition/performance/emissions parameters monitoring, machinery vibration monitoring, infrared radiation and fluid analysis, multi-criteria optimisation techniques and machinery risk analysis will be combinatory used. Data acquisition will be integrated with the ship control systems and the acquired 'big' data will be analysed using statistical and artificial intelligence algorithms and transferred ashore using satellite communications providing decision support and advise for optimal operation/adjustment of the system parameters and the most effective maintenance scheduling. The ISEMMS system development will lead to a significant improvement in the vessels energy efficient operation and the reduction of the operational cost.