Exchange of pre-euro non-legal tender currency for euro is the responsibility of the Central Bank of each individual state.
Maltese coins remained exchangeable for euro until 1st February 2010. Thus they are no longer exchanged by the CB of Malta.
Maltese banknotes of the 5th Series (issued from Sep 1989) can still be exchanged for euro at the Central Bank of Malta, without any additional cost, until 31st January 2018. The Lm10 note of the 4th Series (issued from Mar 1986) is still exchangeable for euro, without any additional cost, at the Central Bank of Malta until 13 September 2010.
The irrevocable fixed exchange rate is 0.429300 Lm per euro.
http://www.centralban...tese_notes_coins.html