Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Nov. 09, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	FUEL TECH, INC.
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		23,167,216
Amendment Flag	false
Entity Central Index Key	0000846913
Entity Filer Category	Accelerated Filer
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	Q3