Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2019
Feb. 21, 2020
Jun. 28, 2019
Document And Entity Information [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2019    
Entity Registrant Name REXAHN PHARMACEUTICALS, INC.    
Entity Central Index Key 0001228627    
Current Fiscal Year End Date --12-31    
Entity Filer Category Non-accelerated Filer    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Well-known Seasoned Issuer No    
Entity Public Float     $ 20,690,919
Entity Small Business true    
Entity Shell Company false    
Entity Emerging Growth Company false    
Entity Common Stock, Shares Outstanding   4,019,141