I am planning to climb Kilimanjaro in December this year. What will be the best sleeping bag and boots tor this trip?
Well, Florin, you're going to want to plan on gear that can take some wet weather. That's not the peak wet season there, but it is a wet season. You likely can expect lots of clouds and fog, and a good chance of rain.
The Valojet GTX
The Valojet GTX
So, for boots, something that will keep you dry and warm. One good choice would be the Lowa Valojet GTX mountaineering boot ($350). These are tough, fairly light boots with uppers of synthetic leather and Cordura, so they wear well and resist moisture. Gore-Tex liners provide a final barrier to wetness. They're pretty good on the trail, and up to most any mountaineering challenge. Asolo's Expert GV boots ($310) would be another good choice—uppers of waterproof Perwanger leather and polyamide fabric, Gore-Tex liners, good cushioning, and gripy outsoles. Fine for the trail, and good for snow and ice as well.
For a sleeping bag, something rated to around 0 degrees F is the best choice. Marmot's Never Summer ($269) meets that spec in a down-filled bag that weighs a bit under four pounds. It has a water-repellent finish to help keep it dry. But moisture still could be an issue. So you might consider a synthetic bag, such as Mountain Hardwear's Lamina +0 ($195). Weighs a little more than a down bag (4 pounds 12 ounces), but if there's a good soaking it will serve you better.
Take a waterproof ground cloth (plastic sheeting is fine). And maybe a vapor barrier liner like RBH Designs' VBL Liner ($100). The VBL gives you lightweight (five ounces) insurance in case temps drop below zero on the upper reaches of the mountain. Which is a distinct possibility.