We consider a model for complex networks that was introduced by Krioukov et al. (Phys Rev E 82 (2010) 036106). In this model, N points are chosen randomly inside a disk on the hyperbolic plane according to a distorted version of the uniform distribution and any two of them are joined by an edge if they are within a certain hyperbolic distance. This model exhibits a power-law degree sequence, small distances and high clustering. The model is controlled by two parameters α and ν where, roughly speaking, α controls the exponent of the power-law and ν controls the average degree.In this paper we focus on the probability that the graph is connected. We show the following results. For α > 1 2 and ν arbitrary, the graph is disconnected with high probability. For α < 1 2 and ν arbitrary, the graph is connected with high probability. When α = 1 2 and ν is fixed then the probability of being connected tends to a constant f (ν) that depends only on ν, in a continuous manner. Curiously, f (ν) = 1 for ν ≥ π while it is strictly increasing, and in particular bounded away from zero and one, for 0 < ν < π.1 This means that the length of a curve γ : [0, 1] → D is given by 2 1 0 (γ 1 (t)) 2 +(γ 2 (t)) 2 1−γ 2 1 (t)−γ 2 1 (t) dt.Random Structures and Algorithms DOI 10.1002/rsa CONNECTIVITY IN A HYPERBOLIC MODEL OF COMPLEX NETWORKS there exists a t 0 such that the probability that a particle of type i ≥ t 0 has a child of type greater than i amongst its children is at most ε. That is:We now set t := 2t 0 . Then we have that z 1 ,z 2 ,···≥0, z t+1 +z t+2 +···>0by condition iii of the lemma. And, if t 0 ≤ i ≤ t then we have: z 1 ,z 2 ,···≥0, z t+1 +z t+2 +···>0 p(i; z 1 , z 2 , . . . ) ≤ z 1 ,z 2 ,···≥0, z i+1 +z i+2 +···>0