Sri Lanka Railways S5 is a class of Diesel multiple unit (DMU) train set built by Hitachi and introduced to Sri Lanka between 1969 and 1970, only two of which were imported. The class was built with modern interior facilities aimed towards the special train tours market and is operated by Sri Lanka Railways.
A one-train set consists of 2 power cars (including the engine) and 3 passenger cars. Previous classes of DMUs in Sri Lanka had only one power car; with their extra capacity, Class S5s could operate on upcountry main lines. Their total passenger capacity is 100.
The train comprises a buffet car and a kitchen; all passenger cars were air conditioned. There was also an automatic door system which was later removed. There was an interior communication system.
This class could be operated in any railway line in Sri Lanka except the Kelani Valley Line. It was only used for chartered services and has performed on the up-country line several times.
In 1970 due to an accident, the engine of No. 720 power car was destroyed. These 717-720 train-sets were later refurbished with only one engine per train.
One S5 DMU (718-719) was chartered by Sri Lanka Airport & Aviation Services Limited and this was repainted in light blue and dark blue livery. The new painted S5's inaugural run was for IIFA Awards guests to Colombo Fort from Katunayake.
<Gallery class="center"> File:Class S5.jpg|<small>Class S5 engine 720 attached to a S5 carriage at the Hydraulic Locomotive Shed, depot for S5s</small> File:SLR S5 718 - 2.jpg|<small>Engine 720 on the approach to Coral Gardens Halt</small> </Gallery>