How to unzip a gz file with VBA

You can install free 7zip archiver (http://www.7-zip.org/) and use shell:
MyFile = "c:\files\test.gz"
Outdir = "c:\out"
Call Shell("c:\Program Files\7-Zip\7z.exe e " & MyFiel & "-o" & Outdir, 1)
Correct path to 7z.exe (you can place it everywhere).

It doesn't work unfortunately. The code executes without error, but the destination directory remains empty.

Try to add quotes before and after path:
MyFile = chr(34) & "c:\files\test.gz" & chr(34)
Outdir = chr(34) & "c:\out" & chr(34)
Cmdstr = "c:\Program Files\7-Zip\7z.exe e " & MyFile & "-o" & Outdir
debug.print CmdStr
Call Shell(Cmdstr,1)
You can test resulting string from command prompt