Reading top-bottom-right-left, the Chinese characters: Hong Kong One Cent
On other random trivia - the Hong Kong mint only operated for several years in the mid 1860s, after which it was dismantled and sold to Japan where it served as the basis for Japan's first milled coinage. Hong Kong's coins from the 1870s onwards were struck at either London or Heaton. After the changeover in gov't in 1997, the Royal Canadian Mint has been producing the circulation coinage.
To expand on the 1-cent: During 1941 an emergency issue of 1-cent notes was issued to tide over the shortage in the coin. Post-WWII, the 1-cent note continued to be issued, though its use primarily was restricted to situations which required exact payment (e.g. taxes, utility bills) as virtually all other transactions were rounded to the nearest 5 cents (a denomination which itself fell out of use in the 1970s)