Two-thirds of civil servants have no idea what the G-Cloud is, it is claimed.
The Whitehall initiative to open up more public sector IT contracts to SMBs is now in its fifth iteration, but a survey of 300 public sector staff by data centre provider Six Degrees Group suggests the scheme is still not widely recognised.
Of the 100 civil servants interviewed at Civil Service Live, an annual event focused on digital transformation in the public sector, just 38 said they had used G-Cloud to procure their own cloud services.
Meanwhile, 66% claimed no knowledge of the framework at all.
More than £217m has been spent on cloud services via the G-Cloud since the Government created it in 2012, with just over half that money going to SMBs as Whitehall tries to cut spending on Big IT suppliers.
But the framework has suffered criticism for being too Whitehall-centric after figures revealed that 26 county councils spent less than 1% of their total IT budget via G-Cloud in 2012/13.
The findings come after a Freedom of Information request from Six Degrees Group last December, when it found 76% of local authorities were not sure how to use G-Cloud.
The firm's group strategy and marketing director, Campbell Williams, said: "These statistics demonstrate that as we move towards the end of 2014, the government still needs to do a lot more to educate all public sector departments on G-Cloud.
"The initiative has the power to transform radically how authorities interact with cloud providers. However, as the findings from both surveys have shown, the public sector remains unaware of the many benefits that using the G-Cloud framework can provide."
G-Cloud director Tony Singleton is undertaking research with public sector IT body Socitm to make G-Cloud more relevant for local government.
But Labour's shadow cabinet office minister Chi Onwurah told CBR last month that local government deserves more ownership of G-Cloud, saying it would give them a louder voice in the digital marketplace.
A Cabinet Office spokesman said: "G-Cloud has come a long way in a short time, with total spend across the public sector reaching nearly £250m up to the end of July, and 60% of this with SMBs.
"We're continuing our work to increase awareness and understanding of the advantages of G-Cloud. Only then can organisations benefit from access to the most innovative, cost-effective solutions by a wide range of suppliers and pass these savings on to the taxpayer.
"For our part, we will continue improving G-Cloud and the Digital Marketplace to make it easier for suppliers and buyers to use."