Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2012	Apr. 03, 2013	Jun. 29, 2012
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2012
Trading Symbol	caon
Entity Registrant Name	Chang-On International, Inc.
Entity Central Index Key	0000042136
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		97,307,366
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well Known Seasoned Issuer	No
Entity Public Float			$ 80,230
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY