The FMSR Class A was the first designated series of locomotives in use by the FMSR. Consisted of 18 4-4-0T tank locomotives originally purchased by numerous state railways, the locomotives served as the FMSR's backbone fleet before the arrival of newer FMSR-ordered locomotives.
The Class A was designated in July 1901 for 12 locomotives originally assigned for both the Perak Railway and Selangor Railway and manufactured between 1884 and 1898, consisting of 11 from manufactured by the Hunslet Engine Company and one from the Selangor Railway produced by Neilson & Company. The Class A designation was further assigned to two 1904 Hunslet locomotives from the Malacca Railway in 1905, and four 1901-1903 Singapore Railway Hunslet locomotives in 1912.
Several Class A Selangor Railway locomotives were known to have been converted to run on oil rather than firewood to cut cost, years before the formation of the FMSR Class A. In addition, the outer cylinders of the Class A were rebuilt with a dimension of 11" by 16" from the original 10" by 16".
The Class A was gradually retired beginning the 1920s when new locomotives were introduced into the FMSR network. From 1912 onwards, certain Class A's were also transferred to the Construction Department; FMSR 71 (Malacca Railway 2) was sold to Siam for use in coal mining assignments in 1924. The last Class A, FMSR 34 (Perak Railway 19), was withdrawn in 1933.