Math documents saved in MathML math files (.mml) can be exported and saved as PDF document using any of the available Math editor, such as for example OpenOffice.org Math. But most office suites have their own program that should be capable of this conversion.
Convert MathML math embedded HTML file to Adobe Portable document format.
We have found one software suitable in our database for this conversion.
Multiplatform software - convert mml to pdf on any platform
Program for mathematical equations from OpenOffice.org suite
Convert from mml file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.