The Australian one-cent coin is the smallest denomination of the Australian dollar. It was introduced with the Currency Act 1965 (Commonwealth) but - unlike some of the other denominations - it did not replace an earlier pre-decimal coin; given that the 5 cents piece replaced the sixpence, one cent was technically equal to 1.2 pence but the Act rounded that to one penny. The one cent coin was much smaller than the penny though, so the penny denomination did not continue to circulate (unlike the sixpence, shilling and florin which were equivalent to respectively 5 cents, 10 cents and 20 cents and were re-denominated as such).
The one cent and the two cent denominations were withdrawn from circulation in February 1992. They have never been demonetised though and remain legal tender.
In 2011, the Royal Australian Mint struck some in silver as an item for collectors. They are of Proof grade only and were issued in a pair (one cent and two cents only, not a full mint set). The coins weigh 2.93 grams and have purity of 0.999 silver (0.0941 oz. ASW).