Today is Bhauma Pradosh, Pradosh vrat on Tuesday (Bhauma vaar / Mangalvaar). Bhauma Pradosh on 28 June 2011 falls in Krishna Paksha of Jyeshta month as per Kannada, Telugu, Marathi and Gujarati calendar. And it falls in Krishna Paksha of Ashad month in North Indian Hindi calendar. The best time to perform Pradosh puja is 4.30 pm to 6 pm.
The next pradosh falls in July i.e. Shukla Paksha of Ashad month in all lunar Hindu calendars in India.
Here is the link to read Pradosha Ashtakam, a prayer to chant during Pradosh Vrat.