The problem stems from your shell interfering with the spaces. Bypass it, thus: 
require IPC::System::Simple;
use autodie qw(:all);
system('D:/OKL/Folder ABC/uncompre', 'temp.gz');

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In reply to Re: system() doesnt recognise director name with spaces by Anonymous Monk
in thread system() doesnt recognise director name with spaces by okl

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