There is an obligation to recite the entire Hallel service on each of the eight days of Hanukah. This obligation applies regardless of whether one prays privately or with a Minyan; in either case, one is required to recite Hallel. Before reciting Hallel, one recites the Beracha, "…Asher Kideshanu Be’misvotav Ve’sivanu Li’gmor Et Ha’Hallel," and after the recitation, one recites the concluding Beracha of "Yehalelucha."
If one mistakenly recited the "half-Hallel" on Hanukah – meaning, he omitted the sections of Hallel that are not recited during Hallel on Rosh Hodesh – then he must repeat the Hallel. However, he does not recite a Beracha before or after his repetition of Hallel.
Women are exempt from the obligation of Hallel. Even though they are included in the obligation of the Hanukah candle lighting, they are nevertheless exempt from the Hallel obligation, just as they are not required to recite Hallel on the Yamim Tobim (Pesah, Shavuot and Sukkot). A woman who wishes to recite the complete Hallel on Hanukah may certainly do so, but she should not recite the Berachot before or after the Hallel.
One may not make any interruptions during the recitation of Hallel. One should not speak at all during Hallel, or use any gadgets – such as cell phones and Blackberry’s – during Hallel. (Of course, one should not be using these gadgets at any point during the prayer service, as this is very disrespectful to the service.) However, if a person hears somebody recite a Beracha while he recites Hallel, he should answer "Amen" to the Beracha. Likewise, one may respond to Kaddish, Kedusha or Barechu during the Hallel recitation. It occasionally happens that the congregation completes Hallel and the Hazzan begins Kaddish before some congregants completed Hallel. They may interrupt their recitation of Hallel in order to answer to Kaddish.
It is interesting to note that there is a verse in the Torah which alludes to the twenty-one days when we recite the complete Hallel. The Torah writes that before the flood, "Shenayim Shenayim Ba’u El Noah" ("two of each [animal] came to Noah" – Bereshit 7:9). The first word, "Shenayim" ("two"), alludes to the first two days of Pesah, when Diaspora communities recite the complete Hallel (as opposed to the other days of Pesah, when the half-Hallel is recited). The second "Shenayim" alludes to the two days of Shabuot, and the word "Ba’u" ("they came") has the numerical value of nine, referring to the nine days of Sukkot, Shemini Aseret and Simhat Torah. Finally, Noah’s name in the phrase "El Noah" may be read as an acronym for the phrase "Ner Hanukah," thus alluding to the eight days of Hanukah, when we recite the full Hallel.
Summary: Men are obligated to recite the complete Hallel on each day of Hanukah; women who wish to recite Hallel may do so, but without the Berachot. One who mistakenly recited "half-Hallel" on Hanukah must recite the whole Hallel, but without the Berachot. One may not make any interruptions during the Hallel recitation, except to answer "Amen" to a Beracha, or to respond to Kaddish, Kedusha or Barechu.
