The Royal Thai Navy will send a team of officers to observe performance tests on the Chinese-built CHD620 submarine engines.
The RTN remains undecided on whether it will accept the engine as a substitute for a German-made MTU396 engine, which the navy had used before.
The Royal Thai Navy (RTN) has decided to postpone the purchase of a second and third submarine for the fourth year running.
The procurement of two other submarines, valued at 22.5 billion baht, is still in limbo, according to a source in the navy.
Thai MPs claimed last year the RTN was duped into buying vessels with no engines.