A brief googling reveals that there are various softwares that can do this but as far as I know none that one can use on a Mac and is easily obtainable is free. A free and easy way to make not just djvu-to-PDF conversion but much more is to use DocsPal which is a free web-based service The site is self-explanatory just upload your djvu file (it will probably recognise the file automatically) choose the output format and hit convert. The file gets converted and a to it appears. One drawback is that when one converts a djvu file to PDF the file size gets significantly larger. I believe this is a general problem about these formats not a shoring on DocsPal's part (but I might be mistaken this problem is mentioned in many discussion threads online). One way of remedying this to reduce the file size using Acrobat (open the converted PDF file select Document Reduce File Size... and follow the instruction) but this does not usually make it as light as the original djvu file (this depends of course on the nature of the data in the file).