For a T x n matrix A = )IaLjll in GF(2) we define a hypergraph G, with n vertices and T hyperedges e, = { j : a , = l}, t = 1, . . . , T . Denote a, = (afl, . . . , a,,), t = 1, . . . , T . A set of row numbers { t l , . . . , t,} is called a critical set if the sum of vectors a f l + . . . + a,_ is the zero vector. In terms of hypergraph G, a critical set can be interpreted as a hypercycle. We can naturally definite the concept of independence for critical sets. Let s ( A ) be the maximal number of independent critical sets in A . The rank r(A) of the matrix A and s ( A ) are connected by the equality r(A) + s ( A ) = T. The total number of critical sets S(A) is equal to FA) -1.Consider the following system of T random equations in GF(2):where i , ( t ) , . . . , i,(t), t = 1, . . . , T are independent identically distributed random variables which take values 1, . . . , n with equal probabilities. Denote A,,n,T the matrix of this system. We prove that the number S(A,,n,T) of critical sets in A r , n , T or hypercycles in GA,,,,T has a threshold property. Let n, T+ and Tln + a. Then for any fixed integer r z 3 there exists a constant a, such that MS(A,,n,T)+O if a