Abstract. Classical Be stars (CBe) are rapidly rotating (Vsin i ∼ 300 km s-1) B-type stars with equatorial circumstellar decretion disks, the production of which is under debate. The Be phenomenon can be understood through the analysis of hydrogen recombination lines in the infrared spectral region. J-band spectroscopy of Be stars is one of the less studied fields in Be star research. We took J-band (11000 - 14000 {\AA}) spectra of 34 CBe stars using the NICMOS instrument available with 1.2 m Mt. Abu infrared observatory. The spectra are interesting due to the presence of neutral oxygen (O I) lines, 11287 and 13165 {\AA}, in addition to Paschen beta and Paschen gamma lines of hydrogen. The optical depth effects in the observed emission lines from the circumstellar disk have been deciphered through the line flux ratio analysis of the Paschen lines. The analysis of the O I lines has been used to understand the role of Lyman-beta fluorescence in the formation of these lines. Also, we used the spectra taken at different epochs separated over 1 year to study the variability in CBe stars.