<P> In 1973, coins were introduced in denominations of 1⁄2, 1, 5, 10 and 25 kobo, with the 1⁄2 and 1 kobo in bronze and the higher denominations in cupro - nickel . The 1⁄2 kobo coins were minted only that year . In 1991, smaller 1, 10 and 25 kobo coins were issued in copper - plated - steel, along with nickel - plated - steel 50 kobo and 1 naira . On 28 February 2007, new coins were issued in denominations of 50 kobo, 1 and 2 naira, with the 1 and 2 naira bimetallic . Some Nigerians expressed concerns over the usability of the ₦ 2 coin . The deadline for exchanging the old currency was set at 31 May 2007 . The central bank stated that the 1⁄2 to 25 kobo coins were withdrawn from circulation with effect from 28 February 2007 . </P> <Ul> <Li> 1⁄2 kobo </Li> <Li> 1 kobo </Li> <Li> 5 kobo </Li> <Li> 10 kobo </Li> <Li> 25 kobo </Li> <Li> 50 kobo </Li> <Li> 1 naira </Li> <Li> 2 naira </Li> </Ul> <P> On January 1, 1973, the Central Bank of Nigeria introduced notes for 50 kobo, 1, 5, 10 and 20 naira . The 50 kobo notes were last issued in 1989 . In 1991, 50 naira notes were issued, followed by 100 naira in 1999, 200 naira in 2000, 500 naira in 2001 and 1000 naira on October 12, 2005 . </P> <P> On February 28, 2007, new versions of the 5 to 50 naira banknotes were introduced . Originally the 10, 20 and 50 naira were to be polymer banknotes, but the 5, 10 and 50 were delayed to late 2009 and only the 20 was released in polymer . The notes are slightly smaller (130 × 72 mm) and redesigned from the preceding issues . In mid-2009 when Sanusi Lamido Sanusi took over as CBN Governor he eventually changed the 5, 10 and 50 naira to polymer notes . </P>

When was 50 naira currency note introduced into nigeria